请小伙伴们分析一下这个逻辑题

西风和瘦马

Scientists have modified feed corn genetically, increasing its resistance to insect pests. Farmers who tried out the genetically modified corn last season applied less insecticide to their corn fields 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 modified seed would be unlikely to increase profits.

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 modification 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 crop
• D.Whether most of the farmers who tried the genetically modified corn last season applied more insecticide than was actually necessary
  

答案选择D，不明白A，A选项说昆虫降低产量，同时杀虫剂跟转基因玉米一样没有效果，而且转基因玉米还贵，这不是说明使用转基因玉米不能增加利润吗，肯定了therefore后面的

Raymonduke

这个OG的题吧。 A里面的sometimes很重要，1）说有的时候这些害虫会减少产量。 那除了这些有些时候以外呢？ 2）评价题就是回答YES或者NO能够削弱或者加强结论，A选项说的时候是否有些时候这些杀虫剂和转基因种子对抗害虫都无效，杀虫剂无效（即便杀虫剂无效，有些时候害虫也可能不会减少产量）能不能使农民利润增长或者不增长，你不知道。 如果能，我觉得有些过度脑补了。所以GMAC的问题用了MOST useful to know? D优于A，如果直接回答YES, 农民的用杀虫剂的成本可能偏高了，现在产出是没什么变化，那么偏多的使用杀虫剂，是会影响利润的。

西风和瘦马

Raymonduke 发表于 2018-1-6 17:48
这个OG的题吧。 A里面的sometimes很重要，1）说有的时候这些害虫会减少产量。 那除了这些有些时候以外呢？  ...

是OG的。评价是否能够增加利润，是我自己又往后推在转基因无效的情况下，转基因和less杀虫药的钱大于原种子和杀虫药的钱用转基因会导致农民成本增加，而玉米产量相同，所以利润减少。
D是最直接的答案，但是无论A的回答是肯定还是否定，现有搭配条件下（使用less杀虫剂和转基因种子）都只能说明使用转基因成本更大。我总觉得应该不管A是肯定还是否定都是一个无关选项，可是不知道漏洞是什么。考试的时候想这么多是会废了的。。。