题目内容
Land animals are believed ______ from sea animals.
A.to have developed |
B.to have been developed |
C.having developed |
D.having been developed |
A
【解析】略
Most people regard zoos as safe places for animals, where struggles such as difficulty finding food and avoiding predators(捕食性动物) don't exist. Without such problems, animals in zoos should live to a ripe old age. But that may not be true for the largest land animals on Earth. Scientists have known that elephants in zoos often develop diseases, joint problems and behavior changes. Sometimes, they even become unable to have babies.
To learn more about how captivity(监禁) affects elephants, a team of international scientists led by Mason, a biologist, compared the life spans of female elephants born in zoos with female elephants living outdoors in the wild. Zoos keep detailed records of all the animals in their care, documenting factors such as birth dates, illnesses, weight and death. These records made it possible for the researchers to analyze 40 years of data on 800 elephants in zoos.
The team found that female elephants born in zoos lived an average of 16.9 years. Their wild counterparts(同类事物) who died of natural causes lived an average of 56 years——more than three times as long.
Scientists don't yet know for sure why wild elephants seem to live so much better than their zoo-raised counterparts. Mason thinks stress and obesity(肥胖) may be to blame. Zoo elephants don't get the same kind of exercise as they do in the wild, and most are very fat. Elephant social lives are also much different in zoos than in the wild, where they live in large groups.
Another finding from the study showed that elephants born in zoos were more likely to die earlier than elephants captured in the wild and brought to zoos. Mason suggests stress in the mothers in zoos might cause them to have babies that are less likely to survive.
The study raises some questions about acquiring more elephants to keep in zoos. While some threatened and endangered species living in zoos reproduce successfully and keep healthy populations, that doesn't appear to be the case with elephants.
【小题1】The text tells us that zoo elephants are different from other zoo animals because they________
A.develop health problems. |
B.1ive to a ripe old age. |
C.are not afraid of predators. |
D.have difficulty eating food. |
A.Female elephants live longer than male elephants. |
B.Female zoo elephants die earlier than their wild counterparts. |
C.Female zoo elephants live longer than their wild counterparts. |
D.Both elephants in zoos and those in the wild live in large herds. |
A.Zoo-born elephants should be attended more carefully |
B.Elephants are no longer an endangered species. |
C.It may not be a wise policy to keep elephants in the zoo. |
D.Zoos should keep more animals except elephants. |
A.Comparison between two species of elephants |
B.Longer lives for wild elephants |
C.Female elephants suffer from poor health. |
D.Longer lives for zoo animals. |
Could a grizzly bear move to your neighborhood? If you live in the U.S. West, the answer may be yes. People and grizzly bears are living closer together now.
The grizzly bear is one of the largest meat-eating land animals in North America. In the early 1800s, about 50,000 grizzly bears lived there. Today there’re far fewer bears. Settlers built cities and roads where bears lived. Many bears were hunted and killed. Now only 1,200 to 1,400 grizzly bears have remained.
In and around Yellowstone National Park, grizzly bears have been making a comeback because of people’s efforts to protect them. Some bears are moving to areas where people live. People are also moving into grizzly countries.
People there have to learn how to live with their new, furry (毛皮的) neighbors peacefully. If someone leaves their barbecue grill(烤肉架)out overnight, or leaves their pet food or rubbish where a bear can get it, the bear will learn to come to their house for food. Grizzly bears that learn to eat people’s food can become dangerous, and they often have to be killed or moved. Also, it’s important not to surprise a grizzly. Besides, if you are hiking in a grizzly country, you should go with others and make a noise to make bears hear your coming and get out of the way. You may not want to invite grizzly bears to your next neighborhood party, but with a little effort, grizzly bears and people can live together peacefully.
【小题1】Why does the number of grizzly bears get smaller, according to the text?
A.Settlers’ buildings break the balance of their living environment. |
B.Land for them to live on is limited and they are hunted in large numbers. |
C.Yellowstone National Park wants to control the number of them. |
D.Living closer to humans makes them die from serious diseases. |
A.One. | B.Two. | C.Three. | D.Four. |
A.exactly 26﹪ | B.over 36﹪ | C.nearly 64﹪ | D.about 96﹪ |
A.Grizzly bears are always friendly to the people living in grizzly countries. |
B.It is certain that grizzly bears and people can live together peacefully. |
C.Grizzly bears are protected only in and around Yellowstone National Park. |
D.The grizzly bear is one of the largest meat-eating animals in North America. |
A.How to protect yourself from grizzly bears. |
B.How to get grizzly bears out of your way. |
C.How to invite grizzly bears to your party. |
D.How to live with grizzly bears peacefully. |