Mycorrhizal fungi (mycorrhizal fungi: 菌根真菌) infect more plants than do any other fungi and are necessary for many plants to thrive, but they have escaped widespread investigation until recently for two reasons. First, the symbiotic association is so well-balanced that the roots of host plants show no damage even when densely infected. Second, the fungi cannot as yet (as yet: adv.至今) be cultivated in the absence of a living root. Despite these difficulties, there has been important new work that suggests that this symbiotic association can be harnessed to achieve more economical use of costly superphosphate fertilizer (superphosphate fertilizer: 过磷酸钙肥料) and to permit better exploitation of cheaper, less soluble rock phosphate. Mycorrhizal benefits are not limited to improved phosphate uptake in host plants. In legumes, mycorrhizal inoculation has increased nitrogen fixation beyond levels achieved by adding phosphate fertilizer (phosphate fertilizer: 磷肥(料)) alone. Certain symbiotic associations also increase the host plant’s resistance to harmful root fungi. Whether this resistance results from exclusion of harmful fungi through competition for sites, from metabolic change involving antibiotic production, or from increased vigor is undetermined.
不懂题目：
18. The level of information in the passage above is suited to the needs of all of the following people EXCEPT:
(A) a researcher whose job is to identify potentially profitable areas for research and product development
(B) a state official whose position requires her to alert farmers about possible innovations in farming
(C) an official of a research foundation who identifies research projects for potential funding
(D) a biologist attempting to keep up with scientific developments in an area outside of his immediate area of specialization
(E) a botanist conducting experiments to determine the relationship between degree of mycorrhizal infection and expected uptake of phosphate
答案是（E）
感觉要有一定的推论啊，可是完全不知道怎么推，也没搜到解析T_T，求助！先谢谢大家！！ 作者: 无敌浩克One 时间: 2015-3-27 15:56:12
还有这道！非常感谢
这篇是非常经典的深海热水口种群内生物数量大增原因探讨的文章
36套ex11
The deep sea typically has a sparse fauna dominated by tiny worms and crustaceans, with an even sparser distribution of larger animals. However, near hydrothermal vents, areas of the ocean where warm water emerges from subterranean sources, live remarkable densities of huge clams, blind crabs, and fish.
Most deep-sea faunas rely for food on particulate matter, ultimately derived from photosynthesis, falling from above. The food supplies necessary to sustain the large vent communities, however, must be many times the ordinary fallout. The first reports describing vent faunas proposed two possible sources of nutrition: bacterial chemosynthesis, production of food by bacteria using energy derived from chemical changes, and advection, the drifting of food materials from surrounding regions. Later, evidence in support of the idea of intense local chemosynthesis was accumulated: hydrogen sulfide was found in vent water; many vent-site bacteria were found to be capable of chemosynthesis; and extremely large concentrations of bacteria were found in samples of vent water thought to be pure. This final observation seemed decisive. If such astonishing concentrations of bacteria were typical of vent outflow, then food within the vent would dwarf any contribution from advection. Hence, the widely quoted conclusion was reached that bacterial chemosynthesis provides the foundation for hydrothermal-vent food chains—an exciting prospect because no other communities on Earth are independent of photosynthesis.
There are, however, certain difficulties with this interpretation. For example, some of the large sedentary organisms associated with vents are also found at ordinary deep-sea temperatures many meters from the nearest hydrothermal sources. This suggests that bacterial chemosynthesis is not a sufficient source of nutrition for these creatures. Another difficulty is that similarly dense populations of large deep-sea animals have been found in the proximity of “smokers”—vents where water emerges at temperatures up to 350℃. No bacteria can survive such heat, and no bacteria were found there. Unless smokers are consistently located near more hospitable warm-water vents, chemosynthesis can account for only a fraction of the vent faunas. It is conceivable, however, that these large, sedentary organisms do in fact feed on bacteria that grow in warm-water vents, rise in the vent water, and then rain in peripheral areas to nourish animals living some distance from the warm-water vents.
Nonetheless advection is a more likely alternative food source. Research has demonstrated that advective flow, which originates near the surface of the ocean where suspended particulate matter accumulates, transports some of that matter and water to the vents. Estimates suggest that for every cubic meter of vent discharge, 350 milligrams of particulate organic material would be advected into the vent area. Thus, for an average-sized vent, advection could provide more than 30 kilograms of potential food per day. In addition, it is likely that small live animals in the advected water might be killed or stunned by thermal and/or chemical shock, thereby contributing to the food supply of vents.
关于这个的主旨题有疑问
18. The primary purpose of the passage is to
(A) describe a previously unknown natural phenomenon
(B) reconstruct the evolution of a natural phenomenon
(C) establish unequivocally the accuracy of a hypothesis
(D) survey explanations for a natural phenomenon and determine which is best supported by evidence
(E) entertain criticism of the author’s research and provide an effective response
答案选D，不过作者并没有明确说哪个好哪个不好啊？？而且最后一段还说了advection（另一种解释原因）可以是替代呢，我感觉作者的意思是两种原因加一起才是最好的解释啊，所以不存在哪个更好吧？作者: 怡阳小煦 时间: 2015-3-27 16:54:52
一点愚见
先看一下文章说了什么：就说一种fungi和roots of host plants生活在一起，很难研究（原因有1、2），但是还是有一些研究成果（共生的好处1(肥料使用更有效)、好处2（来源不知道））。
OK来看题目。不要被花架子吓到了，题目完全可以看成：
The article mentions following EXCEPT:
(A) potentially profitable areas for research and product development
(B) possible innovations in farming
(C) research projects for potential funding
(D) scientific developments in an area
(E) the relationship between degree of mycorrhizal infection and expected uptake of phosphate
E其实错得很明显啊——out of scope，定性和定量的区别。。文中只是定性地说mycorrhizal可以increase，没有定量说to which degree。
先看一下文章说了什么：就说一种fungi和roots of host plants生活在一起，很难研究（原因有1、 ...
万分感谢！一下明白了E为什么错了，还发现了一个新的解题方法！！
还想和你确认一下我的想法是否正确：
A profitable areas指的是有研究价值能获利的地方也就是achieve more economical use of costly superphosphate fertilizer
B 对应to permit better exploitation of cheaper, less soluble rock phosphate.
C我感觉也是对应的A，有利可图所以能获得fund
D跳出现在的圈子所以要研究一个新的，对应 until recently
