多项选择题

Historians and philosophers agree that ever since the development of agriculture, human beings have had an effect on the natural habitat (动、植物生息地) of many plants and animal species. As human populations have increased, as many as 6,000 species are disappearing each year. A number 10,000 times greater than before man appeared on the planet. In one day alone, say scientists, some 45 kinds of plants and animals will die, some 17,500 species will be wiped out. In 1977, the United States Congress took an important step to help the ever-increasing number of endangered species. With the enforcement of the Endangered Species Act, some species have gained more public recognition than others. Elephants and whales, for example, have received far more media attention than have the smaller, less known, and less attractive species that are also endangered. Yet it is the tiny species, such as bugs and bacteria, that keep the planet in balance. Scientists are becoming even more concerned with the fact that without equal concern for these species, the planet’’s biological diversity will be destroyed, leaving us with a loss of potential new food and drugs. On the other hand, some scientists argue that the extinction issue is being exaggerated(夸大) , and that people are "crying wolf" by describing the loss of species as more alarming than it really is. History proves that every species will eventually become extinct. Evolution of species, they say, naturally involves the extinction of species；man has no control. In addition, many people point to the fact that the world is already lacking in resources, food, and adequate health care. Concerned more with economic survival, they ask whether it is, in fact, realistic to make a fuss over saving the elephant or other species that may become extinct many years from now, when people have families to feed tomorrow. These people question a law that puts the continuation of lower forms of life above man s own survival. QUESTIONS： 1. The issue: To what extent we should try to (46) ___________or allow for man’’s development. 2. Proponents’’ (支持者) ( of saving endangered species) arguments: a. The extinction of plants and animals is (47) ___________before man appeared on the planet. b. Tiny species keep the earth in balance. c. Man needs (48) ___________for food and drugs. 3. Opponents’’ (反对者) ( of saving endangered species) arguments: a. Proponents exaggerate the case. b. Species (49) ___________. c. Man’’s need (50) ________.