成人学位英语模拟试题Model Test 4.docxVIP

Model Test 4Part One: Reading Comprehension (40%)Directions: There are 4 passages in this part. Each passage is followed by some questions or unfinished statements. For each of them there are four choices marked A, B, C and D. You should decide on the best choice and mark the corresponding letter on the Answer Sheet by blackening the letter.Passage 1Questions 1 to 5 are based on the following passage:It is clear that some chemicals can damage the health of animals and humans. However, this is not the only problem that can be caused by the careless use of chemicals. Chemicals can also disturb the ecological (生态的) balance of the environment. If the ecological balance is disturbed, the consequences can be extremely serious.很明显，一些化学制品会危害人类和动物的健康。然而，这并不是滥用化学制品导致的唯一问题。化学产品还会危及环境的生态平衡。如果生态平衡遭到破坏，后果将会极端严重。The history of DDT illustrates the problem. DDT, a chemical which kills insects, at first seemed to be a perfect answer to many problems. It would control insects that caused dangerous disease, as well as insects that caused billions of dollars of damage to crops every year. Governments permitted and even encouraged the use of DDT. Farmers in many countries began to spray it on their crops. The immediate results were good. Damage to crops went down, and profits went up. However, the chemical had effects which the scientists did not predict. First, it also killed insects which were the natural enemies of the harmful insects and which were therefore beneficial to farmers. Second, and perhaps worse, DDT did not kill every harmful insect. A few insects had natural resistance to the chemical. They survived and multiplied. In a few years there were large numbers of insects which were not affected by DDT, and there were fewer insects which could act as natural controls on these new “super-insects”. Finally, it became clear that DDT was not solving the insect problem. In fact, it was making the problem worse. It then became necessary to find a second cure for the effects of the fi