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XDF-178 which of the following most logically completes th argument a certain cultivated herb is one of a group of closely related plants that thrive in soil with high concerntrations of metals that are toxic to most other plants. agronomists studying the herb have discovered that it produces large amounts of histidine, an amino acid that, in test-tube solutions, renders these metals chemically inert. Possibily, therefore, the herb's high histidine production is what allows it to grow in metal-high soils, a hypothesis that would gain support if ____. a.histidine is found in all parts of the plant--roots, stem, leaves, and flowers b.the herb's high level of histidine production is found to be associated with an unusually low level of production of other amino acids c.other of the closely related group of plants are also found to produce histidine in large quantities d.cultivation of the herb in soil with high concentrations of the metals will , over an extended period , make the soil suitable for plants to which the metals are toxic e.the concentration of histidine in the growing herb declines as the plant approaches maturity 答案是E，但我实在没弄明白为什么，希望各位大侠能救助 | 
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发表于 2006-8-14 14:48:00
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