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?28. GWD28-Q28:
?Which of the following most logicallycompletes the argument?
?
?A certain cultivated herb is one of agroup of closely related plants that thrive in soil with high concentrations ofmetals that are toxic to most other plants. Agronomists studying the herb have discovered that itproduces large amounts of histidine, an amino acid that, in test-tubesolutions, renders these metals chemically inert.  ossibly, therefore, the herb’s high histidine production is what allows it to growin metal-rich soils, a hypothesis that would gain support if ______.
?
A.histidine is found in all parts of theplant—roots, stem, leaves, and flowers
B.the herb’s high level of histidine production is found to be associatedwith an unusually low level of production of other amino acids
C.others of the closely related groupof plants are also found to produce histidine inlarge quantities
D.cultivation of the herb in soil withhigh concentrations of the metals will, over an extended period, make the soilsuitable for plants to which the metals are toxic
E.the concentration of histidine in the growing herb declines as theplant approaches maturity
答案写是Ｃ。。但是不明白，为什么Ｂ不对呢？Ｂ不是就排除他因了吗？
谢谢解答！！！ | 
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发表于 2011-5-13 22:52:12
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