Understanding the testChoose the

Understanding the testChoose the best answer for each of the following questions according to the test.Our Disappearing Wildlife.1. Animal life first appeared on the earth about 400 million years ago. Through the passing millennia”,thousands of animal species have come and gone. Until recently, this process was gradual, the result of changes in climate, in habitat, or in the genes of the animals themselves. But the tremendous expansion of modern civilization now threatens to upset this natural balance, putting unprecedented pressure on the survival of our wildlife.2. This imbalance can be traced to many causes. Most arise in the greed and poor planning of man himself. With each increase in man’s population, the wilderness areas where the animals live get smaller. The use of pesticides to control injurious insects also harms wild birds and animals. Water pollution kills fish in our rivers, lakes, and oceans. Hunters have almost exterminated many of the larger animals like the bighorn sheep and the grizzly bear. And farmers destroy smaller animals like the prairie dog and the coyote. As a result of this unrelenting pressure, our wildlife is disappearing at the rate of one species or subspecies per year.3. Of all the continents, the most drastic reduction in wildlife has occurred in North America, where the transition from a rural to a highly industrialized society has been most rapid. Among the victims are birds, mammals, and fish. We will never again see the passenger pigeon or the eastern elk. They have been wiped out. Of many other species, only a few representatives still survive in the wild. The U.S. Department of the Interior has put no fewer than 109 species on the endangered species list. (An endangered species is one with poor prospects for survival and in need of protection.) This list includes everything from the timber wolf to the whooping crane . Even the bald eagle, our national symbol, is threatened. 4. Animals that kill other game for food are called predators. The predators include the wolf, mountain lion, fox, bobcat, and bear. Attack against these animals began with the arrival of the first European settlers, who wished to protect their livestock.Eventually, a reward was offered to hunters for every predator that was killed. This reward is called a bounty. Ironically, the Federal government is the chief funder of predator-control programs.5. The settlers also brought with them their Old World fears and superstitions concerning predators. Whether preying on livestock or not, predators were shot on sight. This attitude continues to this day for coyotes, eagles, foxes, mountain lions, and bobcats, and is largely responsible for placing the eastern timber wolf, grizzly bear, and bald eagle on the endangered species list.6. Yet every animal, including the predator, has its place in nature’s grand design. Predators help maintain the health of their prey species by eliminating the diseased, young, old, and injured. Predators like the mountain lion and the wolf help to keep the deer herds healthy. Their kill also provides food for scavengers that feed on carrion. Occasional loss of livestock must be weighed against the good these animals do in maintaining the balance of nature.7. The mountain lion has especially suffered from trapping and hunting. This great cat had the widest distribution of any mammal in the Western Hemisphere. Its range extended from northern British Columbia to the tip of South America , and from the Atlantic to the Pacific.But by the turn of the 19th century, this splendid animal was almost extinct in the eastern United States. In the West, the pattern of persecution was similar to that suffered by other predators. As the sheep and cattle empires grew, so did the war on the mountain lion.8. Overhunting an animal is an obvious form of extermination, but there are more subtle processes that often have the same fatal result. One of these is destruction of habitat. When farmers introduced sheep and cattle to North America, the domestic animals competed with the wild animals for the available grazing land. Animals like the buffalo and the pronghorn antelope, which once roamed the plains in countless numbers, were either killed or pushed off the grasslands. Today, a few remnants of these giant herds are protected from hunters in national game preserves and wildlife refuges. 9. Pesticides have also taken their toll. In 1947 a new chemical poison called DDT was introduced. It proved very effective in controlling insect pests like the potato beetle and the boll weevil. But pesticides, which decompose very slowly, accumulate in animals which feed on pest or their predators, and the accumulated poisons attack their nervous systems. Pesticides also interfere with the formation of calcium in birds , which then lay eggs with very thin shells or no shell at all. When wildlife fail to reproduce, it isn’t very long before they disappear. The bald eagle, 12 species of hawks, and the pelican have been seriously reduced by chemicals.10. Why should we care about the extinction of these birds and animals? The answer is simple enough. Every species that becomes extinct is gone forever. With each departure a small part of the diversity of nature that makes life so interesting is also gone. What has man got to look forward to— endless cities and houses and roads that cross barren country devoid of birds and animals? Is that the world we want for ourselves and our children? 7. If we do not protect our wildlife, the earth will soon beA. devoid of animalsB. consumed by animalsC. overcrowded with animals and birdsD. packed by human beings only
A、A. devoid of animals
B、B. consumed by animals
C、C. overcrowded with animals and birds
D、D. packed by human beings only
【正确答案】：A
【题目解析】：P41