T-3-Q3.

Scientists have made genetic modifications to cotton to increase its resistance to insect pests. According to farmers’ report, 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 farms 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.

正确答案为B，

为什么选B呢？文中是一般种子和被改变了基因的种子的成本的比较，可是B是一般种子和其他种子的比较……

b 是无关项吧；文中没提到棉花和其他农作物的比较呀。

选d；这项可以评价有效性；

仅供参考

选B

题目意思是：前提：新棉花比起以前的棉花来说，1.只轻微减少了杀虫剂的用量;2.产量也没有增加;3种子价格却贵了很多

            结论：新棉花并不能给农民带来经济收益

evaluate题目的方法是取选项的两个极端看是否得到相反的结论。

B中的other crops应该是包括了基因改变过后的棉花。所以假设普通棉花的杀虫剂比其他所有农作物贵,则新棉花减少的杀虫剂量是很大的一笔经济节省；假设普通棉花杀虫剂没有比其他农作物的贵，则采用新棉花是不合算的。

我也赞成选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

比较new cotton & traditional one必须建立在内容可比，条件可比的基础上~D强调了条件可比，我认为D可以直接加强和削弱！！！

我也赞同E