天一串讲阅读理解和完形填空部分.doc

　　阅读理解和完形填空部分 　　(一) 　　The rate of population growth is fastest in underdeveloped countries. In these countries a high birthrate is accompanied by a lowered death rate thanks to improved standards of public health. Ideally it should be possible to counter balance the effect of a reduced death rate by an increased use of family planning. In practice, however, population control is a complex matter. Throughout history people have determined the size of their families according to the cultural values of their societies. 　　 Population control has long been a subject of discussion among researchers. Some have argued that the supply of good land is limited. In order to feed a large population, bad land must be cultivated and the good land overworked. As a result, each person produces less in a given amount of time and this means a lower average income than could be obtained with a smaller population. Other researchers have argued that a large population gives more scope for the development of facilities such as sports, roads and railways, which are not likely to be built unless there is a big demand to justify them. Similarly, it can be argued that the public costs of society will not be so heavy to each individual if they are shared among the members of a large population. 　　 One of the difficulties in implementing birth control lies in the fact that the official attitudes to population growth vary from country to country. In underdeveloped countries where a large population is pressing hard upon the limits of food, space and natural resources, it will be the first concern of government to place a limit on the birthrate. In a welldeveloped society the problem may be more complex. A declining birthrate may lead to unemployment because it results in a shrinking market. Cities with a declining population may have to face the prospect of a shrinking tax base and a fall in land values. If there are fewer children going to school, teachers may be thrown out of work. When the