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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

答案是E，我怎么觉得是D啊？因为histidine inert metals，所以时间长了这片地就没那么toxic了

大家选啥呢？谁能帮忙解释一下啊？？

作者: wsl8028 时间: 2005-10-19 11:35

我选D.w我们需要的假设是Histidin和grow 的关系,正因为histidine inert metals,所以soil 里的metals 被inert了,这样的话metals对其他plants 的toxic 就少了或没有了,当然也就可以生长了,这就说明H和G是有关系的.

为什么不选C呢,因为others of the closely related group of plants正因为和herbs是Close的关系,所以假如Herbs中不一定是H在起作用而是其他的什么东西呢,在它的close group中也是哪个其他的东西在起作用,故并不能说明H就是 G的关键.

作者: titatita 时间: 2006-8-14 12:53

作者: maggiecookies 时间: 2006-9-6 17:39

以下是引用wsl8028在2005-10-19 11:35:00的发言：

zhichi D

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