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标题: 求助TEST 20-6 [打印本页]

作者: Miracle 时间: 2004-1-18 13:11
标题: 求助TEST 20-6
6.Potato cyst nematodes are a pest of potato crops. The nematodes can lie dormant for several years in their cysts, which are protective capsules, and do not emerge except in the presence of chemicals emitted by potato roots. A company that has identified the relevant chemicals is planning to market them to potato farmers to spread on their fields when no potatoes are planted; any nematodes that emerge will soon starve to death.
Which of the following, if true, best supports the claim that the company’s plan will be successful?
(A) Nematodes that have emerged from their cysts can be killed by ordinary pesticides.
(B) The only part of a potato plant that a nematode eats is the roots.？
(C) Some bacteria commonly present in the roots of potatoes digest the chemicals that cause the nematodes to emerge from their cysts.
(D) Trials have shown that spreading even minute quantities of the chemicals on potato fields caused nine-tenths of the nematodes present to emerge from their cysts.
(E) The chemicals that cause the nematodes to emerge from their cysts are not emitted all the time the potato plant is growing.

这是一道说明措施达目的的题，答案是D。但似乎觉得B也有加强的作用在。

作者: 番茄炒蛋 时间: 2004-1-18 14:53
这个b是不行的，这个虫吃什么和农药没有什么关系，它从卵里出来总不能还可以吃空气吧
原文说的是它什么时候会出来，而没有说它吃什么
农药的有效性通过量少效果大最能表现出来

作者: cranberry 时间: 2004-1-18 22:06
B的意思是害虫只吃番茄的根而不是别的部分。而文中说的是根本没有番茄种植的时候，说明它是不是只吃根并不影响公司的计划，因为公司计划在地里没有番茄时使用这个方法。

作者: soimfriend 时间: 2004-11-22 10:34
再请NN讨论一下，我觉得应该选C。题目说chemicals是番茄根自己可以生成的东东，那么农民为什么还要买这个chemicals呢，就是因为番茄根自己产生的chemicals量不足以起作用。C说细菌把番茄根产生的这些chemicals吃了，所以不够，所以才要买。D只是说那个公司生产的chemicals有效，但是如果本来就不缺的话还是没有人买啊。

作者: tempture 时间: 2004-11-22 14:33

A company that has identified the relevant chemicals is planning to market them to potato farmers to spread on their fields when no potatoes are planted; any nematodes that emerge will soon starve to death.

我觉得可能是你没有理解它的意思。题目是说potato的根会分泌一种chemical，nematodes在这种chemical存在的时候才会破茧而出——因为那个时候意味着又吃的了~如果再没有种植的情况下使用chemical，nematodes出来以后不就没有的吃——就都饿死了阿~

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