有木有潜伏在G版的托福党啊，寻找托福口语小伙伴啊！！

无敌浩克OneUID: 3605802

2015.5.29 comprehension note!

The determination of the sources of copper ore used in the manufacture of copper and bronze artifacts of Bronze Age civilizations would add greatly to our knowledge of cultural contacts and trade in that era. Researchers have analyzed artifacts and ores for their concentrations of elements, but for a variety of reasons, these studies have generally failed to provide evidence of the sources of the copper used in the objects. Elemental composition can vary within the same copper-ore lode, usually because of varying admixtures of other elements, especially iron, lead, zinc, and arsenic. And high concentrations of cobalt or zinc, noticed in some artifacts, appear in a variety of copper-ore sources. Moreover, the processing of ores introduced poorly controlled changes in the concentrations of minor and trace elements in the resulting metal. Some elements evaporate during smelting and roasting; different temperatures and processes produce different degrees of loss. Finally, flux, which is sometimes added during smelting to remove waste material from the ore, could add quantities of elements to the final product.
An elemental property that is unchanged through these chemical processes is the isotopic composition of each metallic element in the ore. Isotopic composition, the percentages of the different isotopes of an element in a given sample of the element, is therefore particularly suitable as an indicator of the sources of the ore. Of course, for this purpose it is necessary to find an element whose isotopic composition is more or less constant throughout a given ore body, but varies from one copper ore body to another or, at least, from one geographic region to another.
The ideal choice, when isotopic composition is used to investigate the source of copper ore, would seem to be copper itself. It has been shown that small but measurable variations occur naturally in the isotopic composition of copper. However, the variations are large enough only in rare ores; between samples of the common ore minerals of copper, isotopic variations greater than the measurement error have not been found. An alternative choice is lead, which occurs in most copper and bronze artifacts of the Bronze Age in amounts consistent with the lead being derived from the copper ores and possibly from the fluxes. The isotopic composition of lead often varies from one source of common copper ore to another, with variations exceeding the measurement error; and preliminary studies indicate virtually uniform isotopic composition of the lead from a single copper-ore source. While some of the lead found in an artifact may have been introduced from flux or when other metals were added to the copper ore, lead so added in Bronze Age processing would usually have the same isotopic composition as the lead in the copper ore. Lead isotope studies may thus prove useful for interpreting the archaeological record of the Bronze Age.

21.        The primary purpose of the passage is to
(A) discuss the techniques of analyzing lead isotope composition
(B) propose a way to determine the origin of the copper in certain artifacts
right
(C) resolve a dispute concerning the analysis of copper ore
no dispute, but difficulty
(D) describe the deficiencies of a currently used method of chemical analysis of certain metals
narrow the scope
(E) offer an interpretation of the archaeological record of the Bronze Age
narrow the scope

22.        The author first mentions the addition of flux during smelting (lines 18-21) in order to
(A) give a reason for the failure of elemental composition studies to determine ore sources
the first paragraph talks about the difficulties of varying the elements, and adding flux is presented as the final point. So it must be one of the reasons.
(B) illustrate differences between various Bronze Age civilizations
(C) show the need for using high smelting temperatures
(D) illustrate the uniformity of lead isotope composition
(E) explain the success of copper isotope composition analysis

I did this wrong, because I forgot to take the function of the paragraph into account

23.        The author suggests which of the following about a Bronze Age artifact containing high concentrations of cobalt or zinc?
(A) It could not be reliably tested for its elemental composition.
(B) It could not be reliably tested for its copper isotope composition.
(C) It could not be reliably tested for its lead isotope composition.
(D) It could have been manufactured from ore from any one of a variety of sources.
And high concentrations of cobalt or zinc, noticed in some artifacts, appear in a variety of copper-ore sources.
(E) It could have been produced by the addition of other metals during the processing of the copper ore.

I did this wrong because I didn't go back to check the relative sentence but just select choice based on memory!!!

24.        According to the passage, possible sources of the lead found in a copper or bronze artifact include which of the following?
I.        The copper ore used to manufacture the artifact
II.        Flux added during processing of the copper ore
An alternative choice is lead, which occurs in most copper and bronze artifacts of the Bronze Age in amounts consistent with the lead being derived from the copper ores and possibly from the fluxes.
III.        Other metal added during processing of the copper ore
While some of the lead found in an artifact may have been introduced from flux or when other metals were added to the copper ore, lead so added in Bronze Age processing would usually have the same isotopic composition as the lead in the copper ore.
(A) I only
(B) II only
(C) III only
(D) II and III only
(E) I, II, and III

I did this wrong because I didn't quite understand the meaning of relative sentences

25.        The author rejects copper as the “ideal choice” mentioned in line 33 because
(A) the concentration of copper in Bronze Age artifacts varies
(B) elements other than copper may be introduced during smelting
(C) the isotopic composition of copper changes during smelting
(D) among common copper ores, differences in copper isotope composition are too small
It has been shown that small but measurable variations occur naturally in the isotopic composition of copper. However, the variations are large enough only in rare ores
(E) within a single source of copper ore, copper isotope composition can vary substantially


26.        The author makes which of the following statements about lead isotope composition?
(A) It often varies from one copper-ore source to another.
The isotopic composition of lead often varies from one source of common copper ore to another,
(B) It sometimes varies over short distances in a single copper-ore source.
(C) It can vary during the testing of artifacts, producing a measurement error.
(D) It frequently changes during smelting and roasting.
(E) It may change when artifacts are buried for thousands of years.

27.        It can be inferred from the passage that the use of flux in processing copper ore can alter the lead isotope composition of the resulting metal EXCEPT when
(A) there is a smaller concentration of lead in the flux than in the copper ore
(B) the concentration of lead in the flux is equivalent to that of the lead in the ore
(C) some of the lead in the flux evaporates during processing
(D) any lead in the flux has the same isotopic composition as the lead in the ore
While some of the lead found in an artifact may have been introduced from flux or when other metals were added to the copper ore, lead so added in Bronze Age processing would usually have the same isotopic composition as the lead in the copper ore.
If any lead already has the same isotopic composition, then adding flux won't alter anything
(E) other metals are added during processing

I did this wrong because I didn't understand the meaning of the question.

无敌浩克OneUID: 3605802

2015.5.29 comprehension note!

Classical physics defines the vacuum as a state of absence: a vacuum is said to exist in a region of space if there is nothing in it. In the quantum field theories that describe the physics of elementary particles, the vacuum becomes somewhat more complicated. Even in empty space, particles can appear spontaneously as a result of fluctuations of the vacuum. For example, an electron and a positron, or antielectron, can be created out of the void. Particles created in this way have only a fleeting existence; they are annihilated almost as soon as they appear, and their presence can never be detected directly. They are called virtual particles in order to distinguish them from real particles, whose lifetimes are not constrained in the same way, and which can be detected. Thus it is still possible to define that vacuum as a space that has no real particles in it.

One might expect that the vacuum would always be the state of lowest possible energy for a given region of space. If an area is initially empty and a real particle is put into it, the total energy, it seems, should be raised by at least the energy equivalent of the mass of the added particle. A surprising result of some recent theoretical investigations is that this assumption is not invariably true. There are conditions under which the introduction of a real particle of finite mass into an empty region of space can reduce the total energy. If the reduction in energy is great enough, an electron and a positron will be spontaneously created. Under these conditions the electron and positron are not a result of vacuum fluctuations but are real particles, which exist indefinitely and can be detected. In other words, under these conditions the vacuum is an unstable state and can decay into a state of lower energy; i.e., one in which real particles are created.

The essential condition for the decay of the vacuum is the presence of an intense electric field. As a result of the decay of the vacuum, the space permeated by such a field can be said to acquire an electric charge, and it can be called a charged vacuum. The particles that materialize in the space make the charge manifest. An electric field of sufficient intensity to create a charged vacuum is likely to be found in only one place: in the immediate vicinity of a superheavy atomic nucleus, one with about twice as many protons as the heaviest natural nuclei known. A nucleus that large cannot be stable, but it might be possible to assemble one next to a vacuum for long enough to observe the decay of the vacuum. Experiments attempting to achieve this are now under way.
17.        Which of the following titles best describes the passage as a whole?
(A) The Vacuum: Its Fluctuations and Decay
first paragraph talks about fluctuation, second and third talk about decay
(B) The Vacuum: Its Creation and Instability
(C) The Vacuum: A State of Absence
(D) Particles That Materialize in the Vacuum
(E) Classical Physics and the Vacuum

18.        According to the passage, the assumption that the introduction of a real particle into a vacuum raises the total energy of that region of space has been cast into doubt by which of the following?
(A) Findings from laboratory experiments
(B) Findings from observational field experiments
(C) Accidental observations made during other experiments
(D) Discovery of several erroneous propositions in accepted theories
(E) Predictions based on theoretical work

19.        It can be inferred from the passage that scientists are currently making efforts to observe which of the following events?
(A) The decay of a vacuum in the presence of virtual particles
(B) The decay of a vacuum next to a superheavy atomic nucleus
An electric field of sufficient intensity to create a charged vacuum is likely to be found in only one place: in the immediate vicinity of a superheavy atomic nucleus, one with about twice as many protons as the heaviest natural nuclei known.
(C) The creation of a superheavy atomic nucleus next to an intense electric field
narrow the scope, not only the creation, but its influence on electric field
(D) The creation of a virtual electron and a virtual positron as a result of fluctuations of a vacuum
(E) The creation of a charged vacuum in which only real electrons can be created in the vacuum’s region of space

20.        Physicists’ recent investigations of the decay of the vacuum, as described in the passage, most closely resemble which of the following hypothetical events in other disciplines?
(A) On the basis of data gathered in a carefully controlled laboratory experiment, a chemist predicts and then demonstrates the physical properties of a newly synthesized polymer.
Experiments attempting to achieve this are now under way.
has not desmonstrated
(B) On the basis of manipulations of macroeconomic theory, an economist predicts that, contrary to accepted economic theory, inflation and unemployment will both decline under conditions of rapid economic growth.
(C) On the basis of a rereading of the texts of Jane Austen’s novels, a literary critic suggests that, contrary to accepted literary interpretations. Austen’s plots were actually metaphors for political events in early nineteenth-century England.
(D) On the basis of data gathered in carefully planned observations of several species of birds, a biologist proposes a modification in the accepted theory of interspecies competition.
(E) On the basis of a study of observations incidentally recorded in ethnographers’ descriptions of non-Western societies, an anthropologist proposes a new theory of kinship relations.

I don't understand why there is a prediction in the disputing of an assumption.

21.        According to the passage, the author considers the reduction of energy in an empty region of space to which a real particle has been added to be
(A) a well-known process
(B) a frequent occurrence
(C) a fleeting aberration
(D) an unimportant event
(E) an unexpected outcome
right, One might expect that the vacuum would always be the state of lowest possible energy for a given region of space.
the outcome is contradict to the expectation.

22.        According to the passage, virtual particles differ from real particles in which of the following ways?
they are annihilated almost as soon as they appear, and their presence can never be detected directly. They are called virtual particles
I.        Virtual particles have extremely short lifetimes.
II.        Virtual particles are created in an intense electric field.
III.        Virtual particles cannot be detected directly.
(A) I only
(B) II only
(C) III only
(D) I and II only
(E) I and III only

23.        The author’s assertions concerning the conditions that lead to the decay of the vacuum would be most weakened if which of the following occurred?
(A) Scientists created an electric field next to a vacuum, but found that the electric field was not intense enough to create a charged vacuum.
not relative
(B) Scientists assembled a superheavy atomic nucleus next to a vacuum, but found that no virtual particles were created in the vacuum’s region of space.
mix, the purpose is not to find particles
(C) Scientists assembled a superheavy atomic nucleus next to a vacuum, but found that they could not then detect any real particles in the vacuum’s region of space.
right, the aim is to find decay
(D) Scientists introduced a virtual electron and a virtual positron into a vacuum’s region of space, but found that the vacuum did not then fluctuate.
(E) Scientists introduced a real electron and a real positron into a vacuum’s region of space, but found that the total energy of the space increased by the energy equivalent of the mass of the particles.

无敌浩克OneUID: 3605802

2015.5.29 comprehension note!

Theorists are divided concerning the origin of the Moon. Some hypothesize that the Moon was formed in the same way as were the planets in the inner solar system (Mercury, Venus, Mars, and Earth)—from planet-forming materials in the presolar nebula. But, unlike the cores of the inner planets, the Moon’s core contains little or no iron, while the typical planet-forming materials were quite rich in iron. Other theorists propose that the Moon was ripped out of the Earth’s rocky mantle by the Earth’s collision with another large celestial body after much of the Earth’s iron fell to its core. One problem with the collision hypothesis is the question of how a satellite formed in this way could have settled into the nearly circular orbit that the Moon has today. Fortunately, the collision hypothesis is testable. If it is true, the mantlerocks of the Moon and the Earth should be the same geochemically.

17.        The primary purpose of the passage is to
(A) present two hypotheses concerning the origin of the Moon
right
(B) discuss the strengths and weaknesses of the collision hypothesis concerning the origin of the Moon
narrow the scope
(C) propose that hypotheses concerning the Moon’s origin be tested
narrow the scope
(D) argue that the Moon could not have been formed out of the typical planet-forming materials of the presolar nebula
wrong
(E) describe one reason why the Moon’s geochemical makeup should resemble that of the Earth
wrong

18.        According to the passage, Mars and the Earth are similar in which of the following ways?
I.        Their satellites were formed by collisions with other celestial bodies.
II.        Their cores contain iron.
III.        They were formed from the presolar nebula.
But, unlike the cores of the inner planets, the Moon’s core contains little or no iron, while the typical planet-forming materials were quite rich in iron.
moon is different from Mars or Earth because it doesn't have iron, but both Mars and Earth have iron

(A) III only
(B) I and II only
(C) I and III only
(D) II and III only
(E) I, II, and III

I did this wrong because I didn't read the passage carefully enough.

19.        The author implies that a nearly circular orbit is unlikely for a satellite that
(A) circles one of the inner planets
(B) is deficient in iron
(C) is different from its planet geochemically
(D) was formed by a collision between two celestial bodies
One problem with the collision hypothesis is the question of how a satellite formed in this way could have settled into the nearly circular orbit that the Moon has today.
(E) was formed out of the planet-forming materials in the presolar nebula

20.        Which of the following, if true, would be most likely to make it difficult to verify the collision hypothesis in the manner suggested by the author?
(A) The Moon’s core and mantlerock are almost inactive geologically.
(B) The mantlerock of the Earth has changed in composition since the formation of the Moon, while the mantlerock of the Moon has remained chemically inert.
in this way, scientists can't test whether the Moon and the Earth has the same geochemical characteristics.
(C) Much of the Earth’s iron fell to the Earth’s core long before the formation of the Moon, after which the Earth’s mantlerock remained unchanged.
(D) Certain of the Earth’s elements, such as platinum, gold, and iridium, followed iron to the Earth’s core.
(E) The mantlerock of the Moon contains elements such as platinum, gold, and iridium.

无敌浩克OneUID: 3605802

2015.5.29 comprehension note!

Of the thousands of specimens of meteorites found on Earth and known to science, only about 100 are igneous; that is, they have undergone melting by volcanic action at some time since the planets were first formed. These igneous meteorites are known as achondrites because they lack chondrules—small stony spherules found in the thousands of meteorites (called “chondrites”) composed primarily of unaltered minerals that condensed from dust and gas at the origin of the solar system. Achondrites are the only known samples of volcanic rocks originating outside the Earth-Moon system. Most are thought to have been dislodged by interbody impact from asteroids, with diameters of from 10 to 500 kilometers, in solar orbit between Mars and Jupiter.
Shergottites, the name given to three anomalous achondrites so far discovered on Earth, present scientists with a genuine enigma. Shergottites crystallized from molten rock less than 1.1 billion years ago (some 3.5 billion years later than typical achondrites) and were presumably ejected into space when an object impacted on a body similar in chemical composition to Earth.
While most meteorites appear to derive from comparatively small bodies, shergottites exhibit properties that indicate that their source was a large planet, conceivably Mars. In order to account for such an unlikely source, some unusual factor must be invoked, because the impact needed to accelerate a fragment of rock to escape the gravitational field of a body even as small as the Moon is so great that no meteorites of lunar origin have been discovered.
While some scientists speculate that shergottites derive from Io (a volcanically active moon of Jupiter), recent measurements suggest that since Io’s surface is rich in sulfur and sodium, the chemical composition of its volcanic products would probably be unlike that of the shergottites. Moreover, any fragments dislodged from Io by interbody impact would be unlikely to escape the gravitational pull of Jupiter.
The only other logical source of shergottites is Mars. Space-probe photographs indicate the existence of giant volcanoes on the Martian surface. From the small number of impact craters that appear on Martian lava flows, one can estimate that the planet was volcanically active as recently as a half-billion years ago—and may be active today. The great objection to the Martian origin of shergottites is the absence of lunar meteorites on Earth. An impact capable of ejecting a fragment of the Martian surface into an Earth-intersecting orbit is even less probable than such an event on the Moon, in view of the Moon’s smaller size and closer proximity to Earth. A recent study suggests, however, that permafrost ices below the surface of Mars may have altered the effects of impact on it. If the ices had been rapidly vaporized by an impacting object, the expanding gases might have helped the ejected fragments reach escape velocity. Finally, analyses performed by space probes show a remarkable chemical similarity between Martian soil and the shergottites.
21.        The passage implies which of the following about shergottites?
I.        They are products of volcanic activity.
II.        They derive from a planet larger than Earth.
III.        They come from a planetary body with a chemical composition similar to that of Io.
(A) I only
(B) II only
(C) I and II only
(D) II and III only
(E) I, II, and III
22.        According to the passage, a meteorite discovered on Earth is unlikely to have come from a large planet for which of the following reasons?
(A) There are fewer large planets in the solar system than there are asteroids.
(B) Most large planets have been volcanically inactive for more than a billion years.
(C) The gravitational pull of a large planet would probably prohibit fragments from escaping its orbit.
(D) There are no chondrites occurring naturally on Earth and probably none on other large planets.
(E) Interbody impact is much rarer on large than on small planets because of the density of the atmosphere on large planets.
23.        The passage suggests that the age of shergottites is probably
(A) still entirely undetermined
(B) less than that of most other achondrites
(C) about 3.5 billion years
(D) the same as that of typical achondrites
(E) greater than that of the Earth
24.        According to the passage, the presence of chondrules in a meteorite indicates that the meteorite
(A) has probably come from Mars
(B) is older than the solar system itself
(C) has not been melted since the solar system formed
(D) is certainly less than 4 billion years old
(E) is a small fragment of an asteroid

25.        The passage provides information to answer which of the following questions?
(A) What is the precise age of the solar system?
(B) How did shergottites get their name?
Shergottites, the name given to three anomalous achondrites so far discovered on Earth
it means, shergottites refer to three distinctive achondrites
(C) What are the chemical properties shared by shergottites and Martian soils?
(D) How volcanically active is the planet Jupiter?
(E) What is a major feature of the Martian surface?
Space-probe photographs indicate the existence of giant volcanoes on the Martian surface

I did this wrong, because I didn't understand the sentence meaning, again!

26.        It can be inferred from the passage that each of the following is a consideration in determining whether a particular planet is a possible source of shergottites that have been discovered on Earth EXCEPT the
(A) planet’s size
(B) planet’s distance from Earth
(C) strength of the planet’s field of gravity
(D) proximity of the planet to its moons
(E) chemical composition of the planet’s surface
27.        It can be inferred from the passage that most meteorites found on Earth contain which of the following?
(A) Crystals
(B) Chondrules
(C) Metals
(D) Sodium
(E) Sulfur

无敌浩克OneUID: 3605802

2015.5.29 comprehension note!

It has been known for many decades that the appearance of sunspots is roughly periodic, with an average cycle of eleven years. Moreover, the incidence of solar flares and the flux of solar cosmic rays, ultraviolet radiation, and x-radiation all vary directly with the sunspot cycle. But after more than a century of investigation, the relation of these and other phenomena, known collectively as the solar-activity cycle, to terrestrial weather and climate remains unclear. For example, the sunspot cycle and the allied magnetic-polarity cycle have been linked to periodicities discerned in records of such variables as rainfall, temperature, and winds. Invariably, however, the relation is weak, and commonly of dubious statistical significance.
Effects of solar variability over longer terms have also been sought. The absence of recorded sunspot activity in the notes kept by European observers in the late seventeenth and early eighteenth centuries has led some scholars to postulate a brief cessation of sunspot activity at that time (a period called the Maunder minimum). The Maunder minimum has been linked to a span of unusual cold in Europe extending from the sixteenth to the early nineteenth centuries. The reality of the Maunder minimum has yet to be established, however, especially since the records that Chinese naked-eye observers of solar activity made at that time appear to contradict it. Scientists have also sought evidence of long-term solar periodicities by examining indirect climatological data, such as fossil records of the thickness of ancient tree rings. These studies, however, failed to link unequivocally terrestrial climate and the solar-activity cycle, or even to confirm the cycle’s past existence.
If consistent and reliable geological or archaeological evidence tracing the solar-activity cycle in the distant past could be found, it might also resolve an important issue in solar physics: how to model solar activity. Currently, there are two models of solar activity. The first supposes that the Sun’s internal motions (caused by rotation and convection) interact with its large-scale magnetic field to produce a dynamo, a device in which mechanical energy is converted into the energy of a magnetic field. In short, the Sun’s large-scale magnetic field is taken to be self-sustaining, so that the solar-activity cycle it drives would be maintained with little overall change for perhaps billions of years. The alternative explanation supposes that the Sun’s large-scale magnetic field is a remnant of the field the Sun acquired when it formed, and is not sustained against decay. In this model, the solar mechanism dependent on the Sun’s magnetic field runs down more quickly. Thus, the characteristics of the solar-activity cycle could be expected to change over a long period of time. Modern solar observations span too short a time to reveal whether present cyclical solar activity is a long-lived feature of the Sun, or merely a transient phenomenon.

17.        The author focuses primarily on
(A) presenting two competing scientific theories concerning solar activity and evaluating geological evidence often cited to support them
(B) giving a brief overview of some recent scientific developments in solar physics and assessing their impact on future climatological research
(C) discussing the difficulties involved in linking terrestrial phenomena with solar activity and indicating how resolving that issue could have an impact on our understanding of solar physics
(D) pointing out the futility of a certain line of scientific inquiry into the terrestrial effects of solar activity and recommending its abandonment in favor of purely physics-oriented research
(E) outlining the specific reasons why a problem in solar physics has not yet been solved and faulting the overly theoretical approach of modern physicists

18.        Which of the following statements about the two models of solar activity, as they are described in lines 37-55, is accurate?
(A) In both models cyclical solar activity is regarded as a long-lived feature of the Sun, persisting with little change over billions of years.
(B) In both models the solar-activity cycle is hypothesized as being dependent on the large-scale solar magnetic field.
(C) In one model the Sun’s magnetic field is thought to play a role in causing solar activity, whereas in the other model it is not.
(D) In one model solar activity is presumed to be unrelated to terrestrial phenomena, whereas in the other model solar activity is thought to have observable effects on the Earth.
(E) In one model cycles of solar activity with periodicities longer than a few decades are considered to be impossible, whereas in the other model such cycles are predicted.

19.        According to the passage, late seventeenth and early eighteenth-century Chinese records are important for which of the following reasons?
(A) They suggest that the data on which the Maunder minimum was predicated were incorrect.
The absence of recorded sunspot activity in the notes kept by European observers in the late seventeenth and early eighteenth centuries has led some scholars to postulate a brief cessation of sunspot activity at that time (a period called the Maunder minimum).
some people postulate Maunder minimum based on a lack of record, but Chinese record sth at the same time, so the lacking could result from other reasons which suggests the prediction is wrong.
(B) They suggest that the Maunder minimum cannot be related to climate.
(C) They suggest that the Maunder minimum might be valid only for Europe.
(D) They establish the existence of a span of unusually cold weather worldwide at the time of the Maunder minimum.
(E) They establish that solar activity at the time of the Maunder minimum did not significantly vary from its present pattern.
this is not the function of mentioning Chinese notes at the place of this paragraph

I did this wrong because I ignore the word postulate. I must notice every important word like the attitude mark, verb, adj.

20.        The author implies which of the following about currently available geological and archaeological evidence concerning the solar-activity cycle?
(A) It best supports the model of solar activity described in lines 37-45.
(B) It best supports the model of solar activity described in lines 45-52.
(C) It is insufficient to confirm either model of solar activity described in the third paragraph.
(D) It contradicts both models of solar activity as they are presented in the third paragraph.
(E) It disproves the theory that terrestrial weather and solar activity are linked in some way.
21.        It can be inferred from the passage that the argument in favor of the model described in lines 37-45 would be strengthened if which of the following were found to be true?
(A) Episodes of intense volcanic eruptions in the distant past occurred in cycles having very long periodicities.
(B) At the present time the global level of thunderstorm activity increases and decreases in cycles with periodicities of approximately 11 years.
(C) In the distant past cyclical climatic changes had periodicities of longer than 200 years.
(D) In the last century the length of the sunspot cycle has been known to vary by as much as 2 years from its average periodicity of 11 years.
(E) Hundreds of millions of years ago, solar-activity cycles displayed the same periodicities as do present-day solar-activity cycles.
22.        It can be inferred from the passage that Chinese observations of the Sun during the late seventeenth and early eighteenth centuries
(A) are ambiguous because most sunspots cannot be seen with the naked eye
(B) probably were made under the same weather conditions as those made in Europe
(C) are more reliable than European observations made during this period
(D) record some sunspot activity during this period
(E) have been employed by scientists seeking to argue that a change in solar activity occurred during this period
23.        It can be inferred from the passage that studies attempting to use tree-ring thickness to locate possible links between solar periodicity and terrestrial climate are based on which of the following assumptions?
(A) The solar-activity cycle existed in its present form during the time period in which the tree rings grew.
(B) The biological mechanisms causing tree growth are unaffected by short-term weather patterns.
(C) Average tree-ring thickness varies from species to species.
(D) Tree-ring thicknesses reflect changes in terrestrial climate.
(E) Both terrestrial climate and the solar-activity cycle randomly affect tree-ring thickness.

无敌浩克OneUID: 3605802

2015.5.29 comprehension note!

As of the late 1980’s, neither theorists nor large-scale computer climate models could accurately predict whether cloud systems would help or hurt a warming globe. Some studies suggested that a four percent increase in stratocumulus clouds over the ocean could compensate for a doubling in atmospheric carbon dioxide, preventing a potentially disastrous planetwide temperature increase. On the other hand, an increase in cirrus clouds could increase global warming.
That clouds represented the weakest element in climate models was illustrated by a study of fourteen such models. Comparing climate forecasts for a world with double the current amount of carbon dioxide, researchers found that the models agreed quite well if clouds were not included. But when clouds were incorporated, a wide range of forecasts was produced. With such discrepancies plaguing the models, scientists could not easily predict how quickly the world’s climate would change, nor could they tell which regions would face dustier droughts or deadlier monsoons.

24.        The author of the passage is primarily concerned with
(A) confirming a theory
(B) supporting a statement
(C) presenting new information
(D) predicting future discoveries
(E) reconciling discrepant findings

25.        It can be inferred that one reason the fourteen models described in the passage failed to agree was that
(A) they failed to incorporate the most up-to-date information about the effect of clouds on climate
(B) they were based on faulty information about factors other than clouds that affect climate
(C) they were based on different assumptions about the overall effects of clouds on climate
(D) their originators disagreed about the kinds of forecasts the models should provide
(E) their originators disagreed about the factors other than clouds that should be included in the models

26.        It can be inferred that the primary purpose of the models included in the study discussed in the second paragraph of the passage was to
(A) predict future changes in the world’s climate
(B) predict the effects of cloud systems on the world’s climate
(C) find a way to prevent a disastrous planetwide temperature increase
(D) assess the percentage of the Earth’s surface covered by cloud systems
(E) estimate by how much the amount of carbon dioxide in the Earth’s atmosphere will increase

27.        The information in the passage suggests that scientists would have to answer which of the following questions in order to predict the effect of clouds on the warming of the globe?
(A) What kinds of cloud systems will form over the Earth?
(B) How can cloud systems be encouraged to form over the ocean?
(C) What are the causes of the projected planetwide temperature increase?
(D) What proportion of cloud systems are currently composed of cirrus of clouds?
(E) What proportion of the clouds in the atmosphere form over land masses?

无敌浩克OneUID: 3605802

2015.5.29 comprehension note!

The origin of the theory that major geologic events may occur at regular intervals can be traced back not to a study of volcanism or plate tectonics but to an investigation of marine extinctions. In the early 1980’s, scientists began to look closely at the question of how these extinctions occur. Two paleontologists, Raup and Sepkoski, compiled a master list of marine species that died out during the past 268 million years and noted that there were brief periods during which many species disappeared at once. These mass extinctions occurred at surprisingly regular intervals.
Later studies revealed that extinctions of terrestrial reptiles and mammals also occurred periodically. These findings, combined with the research of Raup and Sepkoski, led scientists to hypothesize the existence of some kind of cyclically recurring force powerful enough to affect living things profoundly. Speculation that so powerful a force might affect geologic events as well led geologists to search for evidence of periodicity in episodes of volcanism, seafloor spreading, and plate movement.

17.        According to the passage, Raup and Sepkoski’s research was concerned with
(A) learning more about the habitats of marine species
(B) studying plate tectonics and the occurrence of volcanism over the past 268 million years
(C) examining extinctions of marine species over the past 268 million years
right: Two paleontologists, Raup and Sepkoski, compiled a master list of marine species that died out during the past 268 million years
(D) finding out whether a rhythmically recurring geologic force exists
this is the later scholars' studying based on what R & S found
(E) confirming previous evidence suggesting that extinction of terrestrial species occurred regularly
not mentioned previous evidence

18.        The author of the passage would most likely describe the findings of Raup and Sepkoski as
the attitude is positive, so eliminate A C D
(A) plausible, because the findings supported the theories of previous researchers
(B) significant, because the findings were an impetus for subsequent research
(C) controversial, because the findings contradicted the theories of previous researchers
(D) questionable, because the authors were not working in their field of expertise
(E) definitive, because the findings confirmed the existence of a rhythmically recurring force
they just proved there was an extinction, not rhythmically thing.

I did this wrong because I didn't know the word impetus and definitive clearly

19.        The author of the passage is primarily concerned with
(A) determining the dates of various geologic events
(B) defending the conclusions reached by Raup and Sepkoski
(C) establishing a link between the disciplines of paleontology and geology
(D) proving that mass extinctions of marine animals occur periodically
(E) explaining how a theory concerning geologic events was formulated

20.        The passage suggests which of the following about the “force” mentioned in lines 16 and 18?
(A) It is responsible for most of the major geologic events that have occurred.
(B) It is responsible for most of the marine extinctions that have occurred.
(C) Its recurrence is unlikely to be able to be predicted by scientists.
(D) Its existence was not seriously considered by scientists before Raup and Sepkoski did their research.
(E) Its existence was confirmed by the research of Raup and Sepkoski.

无敌浩克OneUID: 3605802

2015.5.30 comprehension note!

During adolescence, the development of political ideology becomes apparent in the individual;(TC) ideology here is defined as the presence of roughly consistent attitudes, more or less organized in reference to a more encompassing, though perhaps tacit, set of general principles.(definition of the key conception in TC) As such, political ideology is dim or absent at the beginning of adolescence.(restate TC in the negative expressions) Its acquisition by the adolescent, in even the most modest sense, requires the acquisition of relatively sophisticated cognitive skills: the ability to manage abstractness, to synthesize and generalize, to imagine the future. These are accompanied by a steady advance in the ability to understand principles.(how to get political ideology)

The child’s rapid acquisition of political knowledge also promotes the growth of political ideology during adolescence.(SE, another notion) By knowledge I mean more than the dreary “facts,” such as the composition of county government that the child is exposed to in the conventional ninth-grade civics course. Nor do I mean only information on current political realities.(further clarify what knowledge does child need to acquire) These are facets of knowledge, but they are less critical than the adolescent’s absorption, often unwitting, of a feeling for those many unspoken assumptions about the political system that comprise the common ground of understanding—for example, what the state can appropriately demand of its citizens, and vice versa, or the proper relationship of government to subsidiary social institutions, such as the schools and churches.(further description and example of knowledge) Thus political knowledge is the awareness of social assumptions and relationships as well as of objective facts.(Conclusion 1) Much of the naiveté that characterizes the younger adolescent’s grasp of politics stems not from an ignorance of “facts” but from conventions of the system, of what is and is not customarily done, and of how and why it is or is not done.(naivete is opposite to awareness)

Yet I do not want to overemphasize the significance of increased political knowledge in forming adolescent ideology.(author's attitude, not over support the view in the former paragraph) Over the years I have become progressively disenchanted about the centrality of such knowledge and have come to believe that much current work in political socialization, by relying too heavily on its apparent acquisition, has been misled about the tempo of political understanding in adolescence. Just as young children can count numbers in series without grasping the principle of ordination, young adolescents may have in their heads many random bits of political information without a secure understanding of those concepts that would give order and meaning to the information.(the example of why child can know political ideology does not necessarily require political knowledge)

Like magpies, children’s minds pick up bits and pieces of data. If you encourage them, they will drop these at your feet—Republicans and Democrats, the tripartite division of the federal system, perhaps even the capital of Massachusetts. But until the adolescent has grasped the integumental function that concepts and principles provide, the data remain fragmented, random, disordered.(again, support TC)

21.        The author’s primary purpose in the passage is to
(A) clarify the kinds of understanding an adolescent must have in order to develop a political ideology
the second paragraph talks about what kinds of understanding, the third paragraph define the boundary more accurately
(B) dispute the theory that a political ideology can be acquired during adolescence
contradict
(C) explain why adolescents are generally uninterested in political arguments
not mentioned
(D) suggest various means of encouraging adolescents to develop personal political ideologies
wrong, If you encourage them, they will drop these at your feet
(E) explain why an adolescent’s political ideology usually appears more sophisticated than it actually is


22.        According to the author, which of the following contributes to the development of political ideology during adolescence?
(A) Conscious recognition by the adolescent of his or her own naiveté
mix:
(B) Thorough comprehension of the concept of ordination
contradict: young adolescents may have in their heads many random bits of political information without a secure understanding of those concepts that would give order and meaning to the information.
(C) Evaluation by the adolescent of the general principles encompassing his or her specific political ideas
(D) Intuitive understanding of relationships among various components of society
right, Thus political knowledge is the awareness of social assumptions and relationships as well as of objective facts.
for example, what the state can appropriately demand of its citizens, and vice versa, or the proper relationship of government to subsidiary social institutions
thus, the key to develop political ideology is relationships
(E) Rejection of abstract reasoning in favor of involvement with pragmatic situations
wrong, requires the acquisition of relatively sophisticated cognitive skills: the ability to manage abstractness

I did this wrong because I didn't read this part of the passage carefully enough

23.        The author uses the term “common ground of understanding” (line 27) to refer to
(A) familiar legislation regarding political activity
(B) the experiences that all adolescents share
(C) a society’s general sense of its own political activity
(D) a society’s willingness to resolve political tensions
(E) the assumption that the state controls social institutions

24.        The passage suggests that, during early adolescence, a child would find which of the following most difficult to understand?
(A) A book chronicling the ways in which the presidential inauguration ceremony has changed over the years
(B) An essay in which an incident in British history is used to explain the system of monarchic succession
(C) A summary of the respective responsibilities of the legislative, executive, and judicial branches of government
(D) A debate in which the participants argue, respectively, that the federal government should or should not support private schools
(E) An article detailing the specific religious groups that founded American colonies and the guiding principles of each one
25.        It can be inferred from the passage that the author would be most likely to agree with which of the following statements about schools?
(A) They should present political information according to carefully planned, schematic arrangements.
(B) They themselves constitute part of a general sociopolitical system that adolescents are learning to understand.
(C) If they were to introduce political subject matter in the primary grades, students would understand current political realities at an earlier age.
(D) They are ineffectual to the degree that they disregard adolescents’ political naiveté.
(E) Because they are subsidiary to government their contribution to the political understanding of adolescent must be limited.
26.        Which of the following best summarizes the author’s evaluation of the accumulation of political knowledge by adolescents?
(A) It is unquestionably necessary, but its significance can easily be overestimated.
(B) It is important, but not as important as is the ability to appear knowledgeable.
(C) It delays the necessity of considering underlying principles.
(D) It is primarily relevant to an understanding of limited, local concerns, such as county politics.
(E) It is primarily dependent on information gleaned from high school courses such as civics.
27.        Which of the following statements best describes the organization of the author’s discussion of the role of political knowledge in the formation of political ideology during adolescence?
(A) He acknowledges its importance, but then modifies his initial assertion of that importance.
(B) He consistently resists the idea that it is important, using a series of examples to support his stand.
(C) He wavers in evaluating it and finally uses analogies to explain why he is indecisive.
(D) He begins by questioning conventional ideas about its importance, but finally concedes that they are correct.
(E) He carefully refrains from making an initial judgment about it, but later confirms its critical role.

vinci_gohUID: 3469516

楼主，你做阅读时先通读全文然后做题，还是一边看题目一边看文章？

无敌浩克OneUID: 3605802

vinci_goh 发表于 2015-5-30 20:07
楼主，你做阅读时先通读全文然后做题，还是一边看题目一边看文章？

先读全文

无敌浩克OneUID: 3605802

2015.5.31 comprehension note!

One of the simplest and best known kinds of crystal is the ionic salt, of which a typical example is sodium chloride or ordinary table salt. The fundamental components of an ionic salt are ions: atoms or molecules that have become electrically charged by gaining or losing one or more electrons. In forming sodium chloride, for example, sodium atoms give up an electron (thereby becoming positively charged) and chlorine atoms gain an electron (thereby becoming negatively charged). The ions are attracted to one another by their opposite charges, and they stack together compactly, like tightly packed spheres.
Recently, scientists at Michigan State University created a new kind of crystal called an electride. In electrides, the anions (negative ions) are completely replaced by electrons, which are trapped in naturally formed cavities within a framework of regularly stacked cations (positive ions). Electrides are the first examples of ionic salts in which all these anionic sites are occupied solely by electrons.
Unlike other types of anions, anionic electrons do not behave as if they were simple charged spheres. In particular, because of their low mass and their tendency to interact with one another over great distances, they cannot be “pinned down” to any one location. Instead, they wander close to and among the atoms lining the cavity and interact with electrons in nearby cavities, perhaps changing places with them.
The properties of an electride depend largely on the distance between the cavities that hold trapped electrons. When the trapped electrons are far apart, they do not interact strongly, and so behave somewhat like an array of isolated negative charges. When they are closer together, they begin to display properties associated with large ensembles of identical particles. When they are still closer, the ensemble properties dominate and the electrons “delocalize”: they are no longer tightly bound within individual cavities but are more or less free to pass through the spaces within the frame-work of positive ions.
By synthesizing electrides from a variety of materials, one can vary the geometry of the anionic cavities and their relation to the surrounding cations. The resulting properties may make it possible for electrides to become a basis for economically useful new materials and devices. For instance, because the electrons in some electrides are very weakly bound, these crystals could be effective as photosensitive detectors, in which an impinging photon liberates an electron, resulting in a small electric current. The same weak binding could also make electrides useful in solar-energy converters and as cathodes in batteries. One obstacle is the tendency of electrides to decompose through reaction with air and water. Researchers are seeking ways to increase their stability.
21.        The passage is primarily concerned with discussing
(A) a way to isolate electrons
(B) the characteristics of a new kind of crystal
(C) the structure of an ionic salt
(D) commercial uses for electrides
(E) the properties of ions
22.        In the first paragraph, the author is primarily concerned with
(A) introducing a variant on the standard atomic theory
(B) describing how chlorine atoms can become negatively charged
(C) describing some early research at Michigan State University
(D) presenting the identifying properties of an electride
(E) providing background for the technical discussion to follow
23.        It can be inferred from the passage that the differences between the behavior of anionic electrons and normal anions result from which of the following features of electrons, as compared to normal anions?
I.        The much lower mass of electrons
II.        The much greater tendency of electrons to interact with one another over large distances
III.        The much greater likelihood of electrons to remain trapped in naturally formed anionic cavities
(A) I only
(B) II only
(C) I and II only
(D) I and III only
(E) II and III only
24.        According to the passage, the defining characteristic of an electride is which of the following?
(A) Its positive ions are of particularly low mass.
(B) Its ions possess identical electrical charges.
(C) It contains a framework of regularly stacked ions.
(D) Its ions demonstrate strong mutual attraction.
(E) Its negative ions consist solely of electrons.
25.        It can be inferred from the passage that anions behaving as “simple charged spheres” (line 22) could be expected to
(A) readily lose electrons and become positively charged
(B) move freely in and out of their cavities
(C) respond to photons by liberating electrons
(D) stack with other anions to create a regular framework
(E) remain fixed relative to their cations

26.        It can be inferred from the passage that an electride behaves most like a normal ionic crystal when the electride has which of the following features?
(A) The anionic cavities are widely separated.
(B) All of the trapped electrons are able to delocalize.
(C) The trapped electrons are liberated by impinging photons.
(D) The ions are tightly packed together.
(E) Most of the cations have lost their electrical charge.
  
题干问的是：

从文中推断，一个electride所具有的如下特征中，哪一种表现得最像正常普通的离子晶体？

换句话说，问的是electride在哪方面还和正常的离子晶体是一样的

因为是要求推断做题，所以无法从文中找到直接的对应信息。

谨慎起见，可以用排除法。
选项B说所有的被俘电子都能脱位，文中提到When they are still closer, the ensemble properties dominate and the electrons “delocalize”，这只是针对electride说的，不针对正常的离子晶体

选项C说所有的被俘电子由质子冲击解脱，文中提及the electrons in some electrides are very weakly bound, these crystals could be effective as photosensitive detectors, in which an impinging photon liberates an electron。这也是只针对electride说的

选项D所有的离子都簇拥一团，文中对应信息The ions are attracted to one another by their opposite charges, and they stack together compactly, like tightly packed spheres。这只是针对正常离子而言


选项E多数阳离子都丧失电荷，此内容与文中相关信息不符，which are trapped in naturally formed cavities within a framework of regularly stacked cations (positive ions).   及 more or less free to pass through the spaces within the frame-work of positive ions.
清楚说明electride里阳离子仍然带电，因为本文开始就提到atoms or molecules that have become electrically charged by gaining or losing one or more electrons. 选项本身就是错误的

所以排除法只能选A，electride和普通离子晶体的相同点在：阴离子孔都广泛分离

27.        With which of the following statements regarding electrides would the author most likely agree?
(A) They have proven themselves to be of great commercial value.
(B) Their future commercial value is promising but uncertain.
The resulting properties may make it possible for electrides to become a basis for economically useful new materials and devices.
may = uncertain
(C) They are interesting but of no practical value.
(D) They have commercial value mainly in solar-energy applications.
(E) Their principal importance will lie in scientific research

I didn't read the passage careful enough

无敌浩克OneUID: 3605802

electron  电子
ion  离子
anion  阴离子
cation  阳离子
photon  光子
sodium 钠
choloride  氯
charge 电荷
voltage 电压


diversity emphasizes on changeable

无敌浩克OneUID: 3605802

2015.5.31 comprehension note!
second time reading, so easy

Many objects in daily use have clearly been influenced by science, but their form and function, their dimensions and appearance, were determined by technologists, artisans, designers, inventors, and engineers—using non-scientific modes of thought. Many features and qualities of the objects that a technologist thinks about cannot be reduced to unambiguous verbal descriptions; they are dealt with in the mind by a visual, nonverbal process. In the development of Western technology, it has been non-verbal thinking, by and large, that has fixed the outlines and filled in the details of our material surroundings. Pyramids, cathedrals, and rockets exist not because of geometry or thermodynamics, but because they were first a picture in the minds of those who built them.
The creative shaping process of a technologist’s mind can be seen in nearly every artifact that exists. For example, in designing a diesel engine, a technologist might impress individual ways of nonverbal thinking on the machine by continually using an intuitive sense of rightness and fitness. What would be the shape of the combustion chamber? Where should the valves be placed? Should it have a long or short piston? Such questions have a range of answers that are supplied by experience, by physical requirements, by limitations of available space, and not least by a sense of form. Some decisions, such as wall thickness and pin diameter, may depend on scientific calculations, but the nonscientific component of design remains primary.

Design courses, then, should be an essential element in engineering curricula. Nonverbal thinking, a central mechanism in engineering design, involves perceptions, the stock-in-trade of the artist, not the scientist. Because perceptive processes are not assumed to entail “hard thinking,” nonverbal thought is sometimes seen as a primitive stage in the development of cognitive processes and inferior to verbal or mathematical thought. But it is paradoxical that when the staff of the Historic American Engineering Record wished to have drawings made of machines and isometric views of industrial processes for its historical record of American engineering, the only college students with the requisite abilities were not engineering students, but rather students attending architectural schools.

If courses in design, which in a strongly analytical engineering curriculum provide the background required for practical problem-solving, are not provided, we can expect to encounter silly but costly errors occurring in advanced engineering systems. For example, early models of high-speed railroad cars loaded with sophisticated controls were unable to operate in a snowstorm because a fan sucked snow into the electrical system. Absurd random failures that plague automatic control systems are not merely trivial aberrations; they are a reflection of the chaos that results when design is assumed to be primarily a problem in mathematics.

21.        In the passage, the author is primarily concerned with
(A) identifying the kinds of thinking that are used by technologists
wrong
(B) stressing the importance of nonverbal thinking in engineering design
right
(C) proposing a new role for nonscientific thinking in the development of technology
(D) contrasting the goals of engineers with those of technologists
(E) criticizing engineering schools for emphasizing science in engineering curricula

22.        It can be inferred that the author thinks engineering curricula are
(A) strengthened when they include courses in design
right, Design courses, then, should be an essential element in engineering curricula.
(B) weakened by the substitution of physical science courses for courses designed to develop mathematical skills
(C) strong because nonverbal thinking is still emphasized by most of the courses
(D) strong despite the errors that graduates of such curricula have made in the development of automatic control systems
(E) strong despite the absence of nonscientific modes of thinking

23.        Which of the following statements best illustrates the main point of lines 1-28 of the passage?
(A) When a machine like a rotary engine malfunctions, it is the technologist who is best equipped to repair it.
(B) Each component of an automobile—for example, the engine or the fuel tank—has a shape that has been scientifically determined to be best suited to that component’s function.
(C) A telephone is a complex instrument designed by technologists using only nonverbal thought.
(D) The designer of a new refrigerator should consider the designs of other refrigerators before deciding on its final form.
(E) The distinctive features of a suspension bridge reflect its designer’s conceptualization as well as the physical requirements of its site.
to emphasize the importance of designer

24.        Which of the following statements would best serve as an introduction to the passage?
(A) The assumption that the knowledge incorporated in technological developments must be derived from science ignores the many non-scientific decisions made by technologists.
exactly
(B) Analytical thought is no longer a vital component in the success of technological development.
not mentioned, and wrong
(C) As knowledge of technology has increased, the tendency has been to lose sight of the important role played by scientific thought in making decisions about form, arrangement, and texture.
contradict, should be nonscientific thought
(D) A movement in engineering colleges toward a technician’s degree reflects a demand for graduates who have the nonverbal reasoning ability that was once common among engineers.
not relative
(E) A technologist thinking about a machine, reasoning through the successive steps in a dynamic process, can actually turn the machine over mentally.
not relative

25.        The author calls the predicament faced by the Historic American Engineering Record “paradoxical” (lines 36-37) most probably because
(A) the publication needed drawings that its own staff could not make
(B) architectural schools offered but did not require engineering design courses for their students
(C) college students were qualified to make the drawings while practicing engineers were not
(D) the drawings needed were so complicated that even students in architectural schools had difficulty making them
(E) engineering students were not trained to make the type of drawings needed to record the development of their own discipline
for its historical record of American engineering, the only college students with the requisite abilities were not engineering students, but rather students attending architectural schools.

26.        According to the passage, random failures in automatic control systems are “not merely trivial aberrations” (lines 53) because
(A) automatic control systems are designed by engineers who have little practical experience in the field
(B) the failures are characteristic of systems designed by engineers relying too heavily on concepts in mathematics
right
(C) the failures occur too often to be taken lightly
(D) designers of automatic control systems have too little training in the analysis of mechanical difficulties
(E) designers of automatic control systems need more help from scientists who have a better understanding of the analytical problems to be solved before such systems can work efficiently

27.        The author uses the example of the early models of high-speed railroad cars primarily to
(A) weaken the argument that modern engineering systems have major defects because of an absence of design courses in engineering curricula
(B) support the thesis that the number of errors in modern engineering systems is likely to increase
(C) illustrate the idea that courses in design are the most effective means for reducing the cost of designing engineering systems
(D) support the contention that a lack of attention to the nonscientific aspects of design results in poor conceptualization by engineers
(E) weaken the proposition that mathematics is a necessary part of the study of design

无敌浩克OneUID: 3605802

2015.6.1 comprehension note!

Benjamin Franklin established that lightning is the transfer of positive or negative electrical charge between regions of a cloud or from cloud to earth. Such transfers require that electrically neutral clouds, with uniform charge distributions, become electrified by separation of charges into distinct regions. The greater this separation is, the greater the voltage, or electrical potential of the cloud. Scientists still do not now the precise distribution of charges in thunderclouds nor how separation adequate to support the huge voltages typical of lightning bolts arises. According to one theory, the precipitation hypothesis, charge separation occurs as a result of precipitation. Larger droplets in a thundercloud precipitate downward past smaller suspended droplets. Collisions among droplets transfer negative charge to precipitating droplets, leaving the suspended droplets with a positive charge, thus producing a positive dipole in which the lower region of the thundercloud is filled with negatively charged raindrops and the upper with positively charged suspended droplets.

17.        The passage is primarily concerned with discussing which of the following?
(A) A central issue in the explanation of how lightning occurs
(B) Benjamin Franklin’s activities as a scientist
(C) Research into the strength and distribution of thunderstorms
(D) The direction of movement of electrical charges in thunderclouds
(E) The relation between a cloud’s charge distribution and its voltage

18.        The passage suggests that lightning bolts typically
(A) produce a distribution of charges called a positive dipole in the clouds where they originate
(B) result in the movement of negative charges to the centers of the clouds where they originate
(C) result in the suspension of large, positively charged raindrops at the tops of the clouds where they originate
(D) originate in clouds that have large numbers of negatively charged droplets in their upper regions
(E) originate in clouds in which the positive and negative charges are not uniformly distributed
Benjamin Franklin established that lightning is the transfer of positive or negative electrical charge between regions of a cloud or from cloud to earth. Such transfers require that electrically neutral clouds, with uniform charge distributions,
so before it begets lightning bolts, the cloud is not uniform

19.        According to the passage, Benjamin Franklin contributed to the scientific study of lightning by
(A) testing a theory proposed earlier, showing it to be false, and developing an alternative, far more successful theory of his own
(B) making an important discovery that is still important for scientific investigations of lightning
(C) introducing a hypothesis that, though recently shown to be false, proved to be a useful source of insights for scientists studying lightning
(D) developing a technique that has enabled scientists to measure more precisely the phenomena that affect the strength and location of lightning bolts
(E) predicting correctly that two factors previously thought unrelated to lightning would eventually be shown to contribute jointly to the strength and location of lightning bolts

20.        Which of the following, if true, would most seriously undermine the precipitation hypothesis, as it is set forth in the passage?
(A) Larger clouds are more likely than smaller clouds to be characterized by complete separation of positive and negative charges.
(B) In smaller clouds lightning more often occurs within the cloud than between the cloud and the earth.
(C) Large raindrops move more rapidly in small clouds than they do in large clouds.
(D) Clouds that are smaller than average in size rarely, if ever, produce lightning bolts.
(E) In clouds of all sizes negative charges concentrate in the center of the clouds when the clouds become electrically charged.
ABCD all talk about the size of the cloud which is not included in passage

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想问一下，你每天大概做多少篇阅读呢？