2013年12月四级听力模拟试题十四_大学英语听力

2013年12月四级听力模拟试题十四

　　Questions 26 to 28 are based on the passage you have just heard.

　　26. What is the purpose of the program mentioned in this passage?

　　27. What can we learn from the northern California earthquake in 1989?

　　28. Why did the highway in northern California collapse?

　　Passage Two

　　As a result of pollution, Lake Erie, on the border of the U. S. A. and Canada, is now without any living things.

　　Pollution in water is not simply a matter of poisons killing large numbers of fish overnight. Very often the effects of pollution are not noticed for many months or years. The first organisms to be affected are plants or plankton---the food of fish, birds, and other creatures. When their source of food disappears, the fish and birds die too. In this way, a whole food chain can be wiped out, and it is not until dead fish and water birds are seen at the rivers edge or on the seashore that people realize what is happening.

　　Where do the substances that pollute the water come from? There are two main sources, sewage and industrial waste. As more detergents are used in the home, so more of it is eventually put into our rivers, lakes and seas. Detergents harm water birds by dissolving the natural substances that keep their feathers waterproof. Sewage itself, if it is not properly treated, makes the water dirty and prevents all forms of life in rivers and the sea from receiving the oxygen they need. Industrial waste is even more harmful since there are many highly poisonous substances in it, such as copper and lead.