标题: 求解OG CR69题 [打印本页] 作者: zgzgzg000 时间: 2011-10-10 08:02 标题: 求解OG CR69题 Scientists have modifi ed feed corn genetically, increasing its resistance to insect pests. Farmers who tried out the genetically modifi ed corn last season applied less insecticide to their corn fi elds and still got yields comparable to those they would have gotten with ordinary corn. Ordinary corn seed, however, costs less, and what these farmers saved on insecticide rarely exceeded their extra costs for seed. Therefore, for most feed-corn farmers, switching to genetically modifi ed seed would be unlikely to increase profi ts.
Which of the following would it be most useful to know in order to evaluate the argument?
(A)Whether there are insect pests that sometimes reduce feed-corn yields, but against which commonly used insecticides and the genetic modifi cation are equally ineffective
(B)Whether the price that farmers receive for feed corn has remained steady over the past few years
(C)Whether the insecticides typically used on feed corn tend to be more expensive than insecticides typically used on other crops
(D)Whether most of the farmers who tried the genetically modifi ed corn last season applied more insecticide than was actually necessary
(E)Whether, for most farmers who plant feed corn, it is their most profitable crop 答案选的D，这道题我咋觉得没一个选项看着顺眼的啊 ABCE我也知道都不对 D中，要是most of the farmers who tried the genetically modified corn last season applied more insecticide than was actually necessary ，是加强了原文观点，说明使新基因corn的costs更多，但是反过来most of the farmers who tried the genetically modified corn last season did not applied more insecticide than was actually necessary ，那不是什么都说明不了么？请各位大牛帮着看看！谢谢~~作者: squall2284 时间: 2011-10-10 08:37
A的话，如果害虫对用了农药的和新的作物危害是一样的，那说明新的作物对害虫的抵制是有效的，但是如果是不一样的，没有说明对用了农药的危害比新作物大，还是比新作物小……这个没有办法说明是削弱还是加强。而且这里说了2个产量一样的，害虫主要影响的是产量，这里主要是农药使用的减少来增加收益，和害虫关系不大。 B的话，过去的价格不能说明未来也会如此 C的话把范围扩大了……弄了个无关的东西进来 D的话，如果农民使用的农药数量比实际需要的多，那就说明这种新作物的效果可能会比实际出来的要更好，是削弱，如果试用的农药数量已经比实际需要的少了，那么真正的收益可能还是不变。 E的话是不是收益最大的，和最后收益会不会增加没关系 其实我觉得这段话主要就是通过杀虫剂的支出和产量之间的关系来判断收益会不会增加，因为产量是不变的，所以主要通过杀虫剂的cost来判断，所以可以直接选出D作者: zgzgzg000 时间: 2011-10-15 10:22
明白了 我理解错了一开始~作者: 大北冥星辰 时间: 2011-10-15 11:46
我还是没太明白,你能在解释一下么，按照D要是使用的农药多余平常量，那说明结论是正确的，要是使用的比常量少能说明什么呢？作者: yanjin19891008 时间: 2012-4-4 17:06
我有点不明白d是削弱吗，不是说农民在genetically modified corn 上用的农药更多，也就是说用新作物更费钱了吗，那农民应该更不会选这种作物了吧？哎呀，头！！