OG12 CR69 提问。

zkbeckham

如题，请中文叙述逻辑。谢谢啦
然后这种评价题关键是什么啊。

cyuyolanda

楼主下次把题目贴出来吧


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 crops
(D)    Whether most of the farmers who tried the genetically modified 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

基因改良的谷物可以减少杀虫剂的使用。但是，改良谷比普通谷种子价格高。虽然改良谷减少杀虫剂的使用费用，但仍不能弥补种子价格高的那部分。作者的结论是用基因改良的谷不能增加profit。

做题关键：
做evaluate题的关键就是看它能不能support或者weaken结论，在这道题里的话，就看哪个选项能对”profit比较“产生影响。你先假设选项成立，然后再取非，看看对结论是不是有相反的影响。

BCE没什么关系，轻松排除
A两种谷物都不能抵御的虫子，同时施加影响，profit不变动
D如果对改良谷多施杀虫剂，那么剪掉那一部分杀虫剂，profit变动，所以结论会就被影响了。选这个

zkbeckham

cyuyolanda 发表于 2013-4-22 18:38
楼主下次把题目贴出来吧

接受意见，下次一定贴题目。
但是这个题目，你的解释，我还是没想明白。
你说先假设d成立是对的，那么确实改良谷物不会盈利，再取非，喷的杀虫剂没有多于需要，那么就可以回到题目说的，传统谷物成本低，并且在杀虫剂节约的钱远远大于改良谷物的成本，作者就觉得不会盈利。。。
whatever，很混乱了

cyuyolanda

如果D成立的话，也就是改良谷施多了肥，所以可能实际总cost是比ordinary的低的
但是如果D不成立，那么就是ordinary更便宜了

maestri

这道题就是钱的问题：节省的钱=节省的买药钱-增加的种子钱。  
种子钱不变的情况下，看买药钱有没有的再节省可能性，能再节省的话，自然profit会增加。
D选项提供了这种可能性。如果之前用药过量，那自然可以再少用些，多节省些，profit自然上去