We know that even single exposures to these chemicals, if the amount is large enough, can cause extremely severe poisoning. But this is not the major problem. The sudden illness or death of farmers， farm-workers,and others exposed to sufficient quantities of pesticides is very sad and should not occur. For the population as a whole，we must be more concerned with the delayed effects of absorbing small amounts of the pesticides that invisibly pollute our world.
I Responsible public health officials have pointed out that the biological effects of chemicals are accumulative (累积)over long periods of time,and that the danger to the individual may depend on the sum of the exposures received throughout his lifetime. For these very reasons the danger is easily ignored. It is human nature to shake off what may seem to us a threat of future disaster. “Men are naturally most impressed by diseases which have obvious signs，，，says a wise physician?Dr. Rene Dubos, “yet some of their worst enemies slowly approach them unnoticed. ”
1. Which of the following is closest in meaning to the sentence “Man.. ? is part of nature” (Para. 1，Line 4)?
A. Man appears indifferent to what happens in nature.
B. Man acts as if he does not belong to nature.
C. Man can avoid tie effects of environmental pollution.
D. Man can escape his responsibilities for environmental protection.
讲解答案：
B 句子理解题。“Man(however much he may like to pretend the contrary,is a part of nature. ”意为 不管人们怎样装作自己是自然以外之物,但他终究是自然的一部分。文中“contrary”本意为“相反的事物”，这里与自然相对指自然以外之物，因此B为正确选项。
