36套E12求高手解答

jackalsinUID: 3460507

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  
5 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  
10 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  
15 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.  
20 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  
25 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.  
30 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  
35 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  
40 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  
45 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  
50 studies may thus prove useful for interpreting the  
archaeological record of the Bronze Age.  
(473 words)  


7. 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  
(E) other metals are added during processing



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答案是D，当初做的时候没怎么敏感这个any，我就是想问一下，AC是从哪里看出来错的。。。。。。

411123879UID: 3464402

我觉得这道题其实不是真正意义上的排除题。题目你把except去掉，再把动词取非就变成了
the use of flux in processing copper ore cannot alter（the same） the  
lead isotope composition of the resulting metal when
然后再定位，主要讲铅的同位素在最后一段的最后一部分，最后再定位到第45-49行
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
红色对应的是题干，蓝色对应的是答案

jackalsinUID: 3460507

411123879 发表于 2014-8-23 11:05
我觉得这道题其实不是真正意义上的排除题。题目你把except去掉，再把动词取非就变成了
the use of flux in ...

感谢回答，但是我看了答案之后很容易选出D，但是对于AC真的是看不出来啊，按照您的方法，确实可以解释，但是我觉得这样变化貌似对题干原本意思是有影响的吧，比如“我可以在任意姿势下进食，除了趴在水中”和“我不能在水中进食”，逻辑上是有loop hole的吧