PREP 2007 CR 2 第22题 求点拨

毛阿伦

22.(28162-!-item-!-188;#058&003858)

Herbicides allow cereal crops to be grown very efficiently, with virtually no competition from weeds.In Britain, partridge populations have been steadily decreasing since herbicide use became widespread.Some environmentalists claim that these birds, which live in and around cereal crop fields, are being poisoned by the herbicides.However, testsshow no more than trace quantities of herbicides in partridges on herbicide-treated land.Therefore, something other than herbicide use must be responsible for the population decrease.

Which of the following, if true about Britain, most seriously weakens the argument?

(A) The elimination of certain weeds from cereal crop fields has reduced the population of the small insects that live on those weeds and that form a major part of partridge chicks' diet.

(B) Since partridges are valued as game birds, records of their population are more carefully kept than those for many other birds.

(C) Some of the weeds that are eliminated from cereal crop fields by herbicides are much smaller than the crop plants themselves and would have no negative effect on crop yield if they were allowed to grow.

(D) Birds other than partridges that live in or around cereal crop fields have also been suffering population declines.
（E） The toxins contained in herbicides typically used on cereal crops can be readily identified in the tissues of animals that have ingested them.

求点拨，上文的结论是“Therefore, something other than herbicide use must be responsible for the population decrease.”，削弱的话应该是E，为什么答案是A呢？

hansomecd

Most Weaken

E 只是说toxins can be identified, 跟population decrease无关.
A 打破了因为 balabala 所以 herbicide is not responsible 的逻辑推理，提出了 balabala所以 herbicide is responsible.

毛阿伦

谢谢啦，受用~~

毛阿伦

想通了，把自己的思路发上来：
“Herbicides allow cereal crops to be grown very efficiently, with virtually no competition from weeds” 在不知道Herbicides是除草剂的情况下，同样可以知道H和weeds之间关系是互不相容的。在答案A中描述了weeds对partridge的重要性，没有weeds就会造成P的减少，因此H还是间接造成了P的减少。削弱了结论。

错题分析：当出现不同名词时应该记住彼此之间的关系，即使有不认识的单词。

至于E选项楼上说的很对！

vicccgo

However, tests show no more than trace quantities of herbicides（排除E的重点，是quantities不够，不是没有能识别） in partridges on herbicide-treated land.