Where do pesticides fit into the picture of environmental disease? We have seen that they now pollute soil,water and food, that they have the power to make our streams fishless and our gardens and woodlands silent and birdless. Man, however much he may like to pretend the contrary, is part of nature. Can he escape a pollution that is now so thoroughly distributed throughout our world:

　　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, farmworkers, 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.

　　Responsible public health officials have pointed out that the biological effects of chemicals are cumulative over long periods of time, and that the danger to 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."

　　练习题：

　　Choose correct answers to the question:

　　1.Which of the following is closest in meaning to the sentence "Man…is part of nature" (Para. 1, Lines 3-4)?

　　A. Man appears indifferent to what happens in nature.

　　B. Man acts as if he does not belong to nature.

　　C. Man can avoid the effects of environmental pollution.

　　D. Man can escape his responsibilities for environmental effects of pesticides?

　　2. What is the author"s attitude toward the environmental effects of pesticides?

　　A. Pessimistic

　　B. Indifferent

　　C. Defensive

　　D. Concerned

　　3. In the author"s view, the sudden death caused by exposure to large amounts of pesticides _____.

　　A. is not the worst of the negative consequences resulting from the use of pesticides

　　B. now occurs most frequently among all accidental deaths

　　C. has sharply increased so as to become the center of public attention

　　D. is unavoidable because people can"t do without pesticides in farming

　　4. People tend to ignore the delayed effects of exposure to chemical because _____.

　　A. limited exposure to them does little harm to people"s health

　　B. the present is more important for them than the future

　　C. the danger does not become apparent immediately

　　D. humans are capable of withstanding small amounts of poisoning

　　5. It can be concluded from Dr. Dubos remarks that _____.

　　A. people find invisible diseases difficult to deal with

　　B. attacks by hidden enemies tend to be fatal

　　C. diseases with obvious signs are easy to cure

　　D. people tend to overlook hidden dangers caused by pesticides

　　1.[B] 题干的句子是文章第1段第3句，这是一个带有插入语的简单句，contrary在此表示跟part of nature相反，因此答案为B。

　　2.[D] 第2段最后一句提到，我们必须更加关注吸收少量杀虫剂的潜在后果，它们正在不知不觉地污染我们的世界。因此，作者对杀虫剂对环境的影响关注且担忧,D符合题意。

　　3.[A] 第2段第2句提到，杀虫剂使人突然发病或者死亡是很令人难过的亊，对于人口整体来说，人类对杀虫剂长期累计的潜在后果的认识不足，才是最严重的问题，故选A。

　　4.[C] 根据第3段倒数第2句说的“对未来的灾难无动于衷是人的本性”以及最后一句说的"大多数人只对有明显迹象的疾病予以关注”可知C正是人们忽视化学药物的潜在危害的原因，故选C。

　　5.[D] Dubos博士话中“最可怕的敌人”指的是“杀虫剂引起的潜在危险”，博士话中的slowly approach them unnoticed直接表明D正确。