【OG12-CR-69】 求教！

JessicaHuo

69.
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

此题做了两次都选得A。
OG解释：To answer a question such as this, one should look for information that would strengthen or weaken the argument. If one had information that the farmers growing the genetically modified corn could have increased their yields last year at lower cost, this would be helpful in evaluating the argument, because this would show that the argument is weak.

这个题我在论坛上也找到几个帖子，虽然基本认可D，但觉得D本身也不够严密，先写一下自己的思路，可能啰嗦一些。。

文中在yield、cost等方面对比转基因种子和普通种子，问评价用转基因种子是否能增加利润。根据文章，就需要看转基因种子cost的增加与农药使用量的减少，二者比较大小。现在文中说农药的save rarely exceed the extra cost。

看D选项。若回答yes，即农药用多了，那么减少农药使用量之后，农药save增加，超过extra cost的话，可得出结论：用转基因种子能获利。 若回答no，农药用量合适，那么农药save确实小于extra cost，则转基因种子不能增加利润。

但是D选项回答yes的时候还是有小BUG的，减少农药使用量之后，农药的save一定能超过extra cost吗？这个不够严密吧，还是我的推理或者理解出现问题了。。。找到的两个关于这个题的讨论题年代久远，估计发帖人早已飞越太平洋在美帝生活了，所以把自己的想法贴在这里，能看到的亲们来讨论一下吧~

louisehu

个人拙见~
A选项的话，如果正确-->那就是无论转基因corn还是普通corn都会减少一样产量-->不影响profit；取非are not equally ineffective-->你不能肯定究竟是哪个更ineffective-->哪个产量大哪个产量小-->得不到结论   
D选项的话：如果正确-->农民用多了杀虫剂-->这部分多用的可以转换为利润-->weaken结论；取非-->用的杀虫剂是适量的-->support了结论
通过A选项，你还是不能判定profit增加或减少；我记得evaluate题应该是【选项的成立与否】是【能够削弱/加强argument】，而A选项不符合。

winnielxx

其实关键是看 what these farmers saved on insecticide rarely exceeded their extra costs for seed.这句话怎么理解。楼主是怎么理解的？我觉得这道题是目的题，就是评价选项能否让profit增加或者减少，D选项如果要知道，是可以确定profit的，如果超了了necessary，就是不会超过一般种子的，如果没超过，就回到如何理解上面那句话了，。。。。上面那句话我没看懂。。。