2. 外语
  3. Over the last 40 years there has been a great increase not only in the number of agricultural pesticides in use but also in the

Over the last 40 years there has been a great increase not only in the number of agricultural pesticides in use but also in the

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问题 Over the last 40 years there has been a great increase not only in the number of agricultural pesticides in use but also in the care and sophistication with which they are used by farmers. Nevertheless, the proportion of agricultural crops lost to certain pests worldwide has increased over the same period, even when the pests concerned have not developed resistance to existing pesticides. Which of the following, if true, best explains how improvements in pesticide use have been accompanied by greater losses to certain pests?
选项 A、Some dangerous but relatively ineffective pesticides common 40 years ago are no longer in widespread use.
B、As pesticides have become increasingly pest-specific, controlling certain pests with pesticides has turned out to cost more in many cases than the value of crop losses caused by those pests.
C、Because today’s pesticides typically have more specific application conditions than did pesticides in use 40 years ago, today’ s farmers observe their fields more closely than did farmers 40 years ago.
D、Certain pest-control methods that some farmers use today do not involve the use of chemical pesticides but are just as effective in eliminating insect pests as those that do.
E、Eorty years ago, much less was known about the effects of pesticides on humans and other mammalian species than is now known.
答案B
解析 本题为解释题型，让我们寻求一个选项去解释为什么杀虫剂使用方面的改进伴随某些害虫的损失却更大。(B)说明由于单个针对性增强，导致用杀虫剂控制某种害虫的成本变得比那种害虫带来的损失的价值更大，与我们要解释的相吻合，起到了解释作用，因此(B)正确；(A)选项起到部分反对作用；(C)只是解释了农民为什么更仔细；(D)说的是共同点，无法解释上面的似乎不合常理的说法；(E)为新比较，且了解程度与损失等无关
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