请教prep-2-22 cr 万分感谢

beryl8

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, tests show 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.


答案选A， 可是E为什么不对呢？这句herbicidetests show no more than trace quantities of herbicides in partridges on herbicide-treated land.是什么意思呢？谢谢！！

sindyxu2009

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, tests show 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.


答案选A， 可是E为什么不对呢？这句herbicidetests show no more than trace quantities of herbicides in partridges on herbicide-treated land.是什么意思呢？谢谢！！

-- by 会员 beryl8 (2010/8/17 21:52:41)

A说的是由于杂草的消失使得某种小昆虫的数量下降，而这种昆虫是partridge鸟的主要食物。（所以说明是由于除草剂的使用导致partridge的减少，削弱原结论）
E说的是如果动物吞下除草剂中的毒素，那么这种毒素是会在动物的组织中被检测到的。（E项不对的原因就是因为楼主从题干中找出的这句话，意思是说除草剂检测显示说在用了除草剂的范围里的partridges鸟身上几乎没有除草剂残留. "no more than trace quantities of herbicides"即“不比微量多”）
……水平有限，大家讨论下吧~

JuggernautZNJ

感觉A选项有点牵强。如果是除草剂杀死了小昆虫，partridge因为吃小昆虫而致死，按照选项的逻辑，应该是除草剂通过食物链导致了partridge死亡，那么怎么会“herbicidetests show no more than trace quantities of herbicides in partridges on herbicide-treated land”，关于这点不是很明白，希望NN指点。

beryl8

谢谢sindyxu2009 的讲解非常清楚，我明白了！！！

JuggernautZNJ

想明白了~~~

sindyxu2009

感觉A选项有点牵强。如果是除草剂杀死了小昆虫，partridge因为吃小昆虫而致死，按照选项的逻辑，应该是除草剂通过食物链导致了partridge死亡，那么怎么会“herbicidetests show no more than trace quantities of herbicides in partridges on herbicide-treated land”，关于这点不是很明白，希望NN指点。

-- by 会员 JuggernautZNJ (2010/8/17 22:26:22)

我理解的是，除草剂消灭草，所以小虫没有了（数量下降了嘛），所以小鸟吃不到小虫饿死了……所以饿死的小鸟和存在的小鸟都没中毒，所以自然几乎检测不到……

JuggernautZNJ

呵呵，已经想明白了，谢谢！

iamjasmineshi

(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.文中说要weaken的是sth other than herbicide，那么反过来说就应该是herbicide。这个选项说了除去的杂草里的小虫子是幼鸟的主要食物，因此杂草减少，小虫子减少，鸟的数量也减少了。归根结底就是herbicide的原因。
(B) Since partridges are valued as game birds, records of their population are more carefully kept than those for many other birds. 无关选项。
(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. 无关比较。
(D) Birds other than partridges that live in or around cereal crop fields have also been suffering population declines. 一个statement说明其他鸟类也数量减少，不能说明是否是因为herbicide的原因。
(E) The toxins contained in herbicides typically used on cereal crops can be readily identified in the tissues of animals that have ingested them. 和D一样，也只是一个statement，和文中呼应说明了在死鸟的器官里可以检测出这种毒素，BUT, there is no indication which suggests that herbicide shud be responsible for the decrease. Thus, this choice cannot weaken the argument.

LaDuDu

A选项的逻辑还是不能够清楚的削弱原文逻辑
原文逻辑是在这片地里的鸟体内有微量的药，所以，鸟的减少是有其它原因造成的。削弱的终点是，鸟减少的原因还是农药造成的。
A选项农药－》虫子少，虫子少－》鸟少，这一个逻辑线路里中间隔了一层，并不能直接推断出农药就是虫子死亡的原因
第一反应看A选项的时候就是这个完全就是增强了文章逻辑而不是削弱了，刚好找了一个他因（虫子变少）

柒佰佳

LaDuDu 发表于 2017-1-4 17:31
A选项的逻辑还是不能够清楚的削弱原文逻辑
原文逻辑是在这片地里的鸟体内有微量的药，所以，鸟的减少是有其 ...

A选项:除草剂使用过多—>野草变少—>小虫子变少，因此以小虫子为食的鸟也变少。这是除草剂的间接影响。consequence可以包括直接间接两方面。因此削弱了原文：鸟变少与除草剂无关的逻辑。