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28-28: Which of the following most logically completes the argument?
A certain cultivated herb is one of a group of closely related plants that thrive in soil with high concentrations 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. Possibly, therefore, the herb’s high histidine production is what allows it to grow in metal-rich 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: others 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
选d,有一个逻辑错误:题目说那个herb能产生一种东东,让毒素失效.可是他没说那个东东释放到了外面土壤里啊,很可能它就只停留在植物体内发挥作用啊,很多生长素就是这样的,所以也不会对土壤产生影响.
c我觉得是很好的加强啊,一种herb有了histidine,就能帮助它生存,那么其他也能生存的植物也都有那个东东,直接加强结论啊.
open to discuss | 
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发表于 2005-7-15 16:36:00
