Q3:
Scientists have made genetic modifications to cotton to increase its resistance to insect
pests. According to farmers’ reports, the amount of insecticide needed per acre to control insect pests was only slightly lower for those who tried the modified seed than for those who did not. Therefore, since the modified seed costs more than ordinary seed without producing yields of higher market value, switching to the modified seed would be unlikely to benefit most cotton farmers economically.

Which of the following would it be most useful to know in order to evaluate the argument?

A. Whether farmers who tried the modified cotton seed had ever tried growing other
crops from genetically modified seed
B. Whether the insecticides typically used on ordinary cotton tend to be more
expensive than insecticides typically used on other crops
C. Whether for most farmers who grow cotton it is their primary crop
D. Whether the farmers who have tried the modified seed planted as many acres of
cotton, on average, as farmers using the ordinary seed did
E. Whether most of the farmers who tried the modified seed did so because they had
previously had to use exceptionally large quantities of insecticide

答案是B。为什么呀？evaluate的题不是可以用排除法吗，那么B应该是第一个被枪毙的呀？

科学家对棉花进行了基因更改,增加棉花的对害虫的抵抗能力.根据农民的报告,用在每亩更改基因种子上的杀虫剂只比一般种子的少一点点.因此,更改基因的种子比一般的种子要贵,然而又不能产生更高的市场价值,所以转向用更改基因种子并不能使农民在经济上受益.

1.杀虫剂用得少一点点

2.成本贵

3.不能卖到更高的价钱

表面上农民是不能受益的.不能卖到更高的价钱已经是确定了的,那么我们只能在这两种棉花种子没进入市场前来做文章了.不能卖到更高的价钱,如果成本能降下来,农民还是能受益的;如果成本降不下来,那么如结论所说,农民无法受益.

基因更改后的种子对害虫的抵抗能力要高,虽然用的杀虫剂只是少一点,如果用的杀虫剂便宜一些呢?成本由两部分构成:买种子和把种子培育成熟过程中的消费(在这里也就是杀虫剂上的花费),买种子已经要比普通的种子要贵,那么如果在杀虫剂的消费要便宜的话,也不能说更改基因的种子比普通的种子成本会高.

B说的就是这个意思.写了一大堆,不知道说清楚没有!!!

大家讨论一下吧.

可是我觉得B只讲了ordinary cotton和其他crops的关系，没有讲genetic modified cotton的事情呀？

文章里说genetic modified cotton只比ordinary cotton用insecticides稍微少一点。如果加上B，那么说genetic modified cotton用insecticides和其他crops基本持平，这对evaluate没有什么作用呀？

大家帮忙呀！

同问。我在别的几个论坛上看到有说正确答案是D的，

http://bbs.taisha.org/archiver/tid-816237.html

也有说是E的。

http://www.usee.com.tw/driven/blog_article.asp?id=7159

晕了……

本人觉得是D

我也晕了