[单项选择]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
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. (E) Forty years ago, much less was known about the effects of pesticides on humans and other mammalian species than is now known.

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[填空题]The international situation has been growing (increase) ______ difficult for the last few years.

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In recent years, there have been great social and economic changes in the United States. And, these changes have affected almost all of America’s housing system, from home building to home buying.
First of all, American families are becoming smaller. People nowadays are having fewer children, or choosing not to halve children at all. Many people are marrying later in life. And about 40% of all American marriages end in divorce.
All this means that many Americans now want smaller houses. And a large percentage are buying apartments.
This has created a shortage of rental housing in many parts of the country. It has caused special difficulties for those who are old or poor, and do not have the money to buy a place of their own.
Some people are solving this problem by forming cooperatives. In a cooperative, everyone in an apartment building joins together and buys a share of the building. If 20% of those living in the cooperative have low earning

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