结构推理 Directions: In this part there is a short passage with five questions or incomplete statements. Read the passage carefully. Then answer the questions or complete the statements in the fewest possible words (not exceeding 10 words). Every year in many developing countries large areas of land that once produced food become completely unproductive. The hungry residents of these areas have to move or die. The problem is not caused by pollution; it is not the result of poisonous chemicals which contaminate the land. Pollution is not the only way to destroy the environment. It can be destroyed by humans who disturb the ecological balance of an area in other ways. In any area there is a balance in nature. Each part of the natural system depends on other parts. If one part is disturbed, then the balance of the system is disturbed and other parts begin to suffer. This is the problem that is now threatening the lives of many people in many countries, for example, in Nepal. A number of years ago, the population of Nepal began to increase, especially among the people who lived in the small farms in the mountains. More food and fuel were necessary for the larger number of people, so the farmers in the mountains bought more animals. For fuel and animal food, they cut down more and more of the trees and plants which grew on the sides of the mountains. The farmers did not know that these plants and trees served a very important purpose. They protected the hills from the weather. They held the top soil in place and prevented it from being pushed down the mountain sides by wind and rain. Now without the protection of the trees and plants, the top soil is being washed away by heavy rain. The farmers are losing their land. More and more have to move to the lower areas of Nepal, which are already overpopulated and cannot support a large increase in population. To solve problems like this, it is important that people understand the consequences of their actions. It was not clear to the hill farmers of Nepal that they were to blame for the destruction of their own land. Today environmental scientists are teaching the farmers about ecology. They are also showing them ways to protect their land with new trees and plants. Problems which are similar to the problem in Nepal exist in many countries around the world, but they can be solved. Ecologists are proving to us that actions which give short-term solutions to problems can also have disastrous long-term consequences. If governments and others pay more attention to these scientists, then perhaps they will not make the same type of mistakes that were made in Nepal and in many other countries. 1.Large areas of land become completely unproductive because of 2.Farmers cut down more and more of the trees and plants for 3.More and more farmers have to move to the lower areas of Nepal because 4.The environmental scientists are teaching farmers about ecology in order to 5.What are ecologists proving to us?