标题: prep鸟中毒那题，我彻底晕了 [打印本页] 作者: qiuhua01234567 时间: 2012-1-10 20:54 标题: prep鸟中毒那题，我彻底晕了 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. 我被绕晕了，希望有人帮我分析下，感激。。 作者: lxd19870226 时间: 2012-1-10 21:15
sth other than herbicide use is responsible 需要weaken它 A选项说 杂草的减少是responsible的 但杂草是咋少的呢 还是因为herbicide use 所以就还不是other than herbicide use作者: 墨月雪 时间: 2012-1-10 22:30
B与herbicide无关..排除. C与partridge无关..排除. D偷换主体..讲了其他鸟..排除. E说herbicide中的毒物可以被监测出来..我觉得是个加强..
A是正确的..虽然no more than trace quantities.但是herbicide减少了杂草的数量..杂草少了..虫子就少了..所以partidge就少了.. A其实是给出了另外一个解释..削弱了原题..