OG12 CR69

sleepo

69. 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 profi table crop

看了很多讨论，还是有点不明白D。我的逻辑可能比较奇怪，insecticide是杀虫剂而不是化肥，并不能提高产量，是不是多用了有什么关系呢？

我的答案是A。。。因为如果有一种害虫，如果两种方法都无效，那应该选种子便宜的。。。就是基因改良前的。。。

期待大家的讨论~谢谢！

wangyaoshun

文中的情形：在杀虫剂上省的钱<在基因改良种子上多花的钱，故而不合算
D：Yes的情形：假设一个极端的情况，这种基因改良的种子完全不需要使用杀虫剂，则上面的<变成>号，i.e. 杀虫剂上省的钱>在种子上多花的钱，故而合算
No的情形，<号不变，
即，Yes和No的情形对结果产生了相反的效果，故而正确
A没有这种效果

enkyklios

顶顶顶顶顶顶

辛小白

A你举得是特例 即使存在一种害虫 那么其他害虫呢？
前提是我们知道有那么一种改造过的玉米能更好的抵抗害虫 然而它的亩产量却和普通玉米差不多 选D 回答如果是YES 那么有可能就是由于多用杀虫剂导致改造的玉米亩产量下降 从而不能说明结论的改造玉米不能增加利润（因为如果你把杀虫剂用量减少，产量提高，利润就上升了）

wangyaoshun

辛小白 发表于 2013-6-10 16:58
A你举得是特例 即使存在一种害虫 那么其他害虫呢？
前提是我们知道有那么一种改造过的玉米能更好的抵抗害虫 ...

题目已经说了产量不变了 got yields comparable to those they would have gotten with ordinary corn.这道题目讨论profit, 产量价格不变即是revenue不变，只能考虑cost side，D的yes和no情形恰能导致两种cost的对比，导致profit的对比发生变化，或者说可能的变化
A举特例无效

辛小白

wangyaoshun 发表于 2013-6-10 17:16
题目已经说了产量不变了 got yields comparable to those they would have gotten with ordinary corn.这 ...

这样解释的话 你不是存在了一个假设前提 假设了杀虫剂的花得钱要大于改造花的钱

wangyaoshun

辛小白 发表于 2013-6-10 18:06
这样解释的话 你不是存在了一个假设前提 假设了杀虫剂的花得钱要大于改造花的钱  ...

How come? 改造花的钱是什么？
According to the argument, what these farmers saved on insecticide rarely exceeded their extra costs for seed, you lose money, if the save on insecticide could possibly exceed extra costs for seeds, you can possibly make money. That's the rationale for Evaluate, right? Not to strengthen an argument.