（翻译：正反表达法）The doubt was still unsolved after his repeated explanation. 虽经他一再解释，疑团仍然____

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—By Karl Krahnke

The Book

America in 1962 was still emerging from the comfortable decade of the 1950s, a time in which life generally seemed good and many technological advances of the previous twenty or thirty years promised a happier, healthier, and safer future. But clouds were on the horizon, and many of the questions and doubts that would characterize the decade of the 1960s were already apparent. One cloud that quickly became a major storm took the form. of a book that was published in 1962, Silent Spring. Silent Spring is one of a few books that have changed history.

Silent Spring is about chemicals, specifically about one type of chemical chlorinated hydrocarbons—and more specifically about one famous member of that group, DDT. Many people who have grown up since the 1960s have not heard of DDT, but before Silent Spring, and for a number of years after ward, DDT and its relatives were important tools in the civilized world's at tempt to control nature through the use of technology and chemicals. DDT is a powerful insecticide and was used throughout the world to kill insect pests of all kinds.

DDT had been discovered in 1939 and began to be widely used during the Second World War. For many years it seemed to be just one more miraculous product of modern science. DDT was used to destroy populations of many harmful insects, malaria-carrying mosquitoes, lice, and flies. There is no question that DDT and similar chemicals did, and still are doing, a lot of good. The danger from insect-carried diseases such as malaria and yellow fever has been greatly reduced, and the lives of many people have been saved and lengthened by their use.

Silent Spring, however, told about the other side of DDT and its relatives. Using carefully collected scientific evidence, the author showed that DDT and similar pesticides had at least two dangerous side effects. One of these was the tendency of pesticides to kill all of the insects in the location where they were used. Not all insects are harmful, however. Many bees, for example, perform. necessary functions, such as pollinating plants and even controlling the numbers of other, more harmful, insects. When useful insects are eliminated, the result has often been greater problems than before the pesticide was used. A second problem with chlorinated hydrocarbons is that they do not disappear quickly; they are stable chemicals that accumulate in the bodies of insects and the birds and animals that eat them and continue to do harm when and where the effect was not intended. Birds are especially affected by DDT-type pesticides. Many birds eat insects and worms as food, and the chemicals that were in the insects collect in their bodies, frequently leading to their death. As Silent Spring demonstrated so clearly, the disappearance of many kinds of birds was due to the presence of pesticides in their food sources.

Most importantly, Silent Spring brought to the world at large the beginning of an understanding of modern ecology. We began to see that the natural world we live in is made up of a number of plants, insects, and animals, some good, some not so good, and that we cannot encourage or eliminate some without producing effects in many others, and even in ourselves.

Silent Spring is a powerful book, beautifully and sensitively written, and it carries a strong message. It is full of complex scientific information, but it is equally a very human and caring book. It does not try to present a balanced picture or to find excuses for the mistakes we made with pesticides. It is an argument for a new and different way of looking at nature and our relation ship with nature. The book

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