单选题 Stem borers are insect pests that often ruin North American corn crops. On some other continents, crop damage by stem borers is controlled by a certain species of wasp. Since these wasps cat nothing but stem borers, importing them into North America will keep crop damage from stem borers under control without endangering other North American insect species.
Which of the following is an assumption on which the argument depends?

A、 Corn is the principal food of stem borers that live on continents other than North America.
B、 The wasps are capable of surviving in North America long enough to eat significant numbers of stem borers.
C、 No wasp in North America is closely related to the species of wasp that eats stem borers.
D、 On continents other than North America, the wasps control stem borers more effectively than does any other pest control measure.
E、 (E) Corn crops on continents other than North America are not damaged by any insect pests other than stem borers.

【正确答案】 B

【答案解析】[解析] 推理为：“对蕨类植物的控制可以引入一种蛾子”，这是标准的对目的提问法，解题思路为A可行或A有意义，答案为“释放的蛾子可以充分繁殖以生殖足够多的蛾子来减少蕨类植物且阻碍它的增长”。很明显，本题为这一问题的重考考题，虽没有原样照搬，但其问题目的、段落内容与答案方向完全相同，我们通过比较这两道题，应当认识到熟做真题的重要作用。本题答案方向也为A可行或有意义，所以(B)正确。