Most people think of zoos as safe heavens for animals, where

Most people think of zoos as safe heavens for animals, where problems such as difficulty finding food and avoiding predators (食肉动物) don’t exist. Therefore, 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 suffer from poor health. They develop diseases and they are even unable to have babies.
To learn more about how captivity (圈养) affects elephants, a team of international scientists compared the lifespans (寿命) of the zoo-born elephants with the lifespans of thousands of wild elephants. They also compared some Asian elephants living in zoos with some Asian elephants which work in logging camp (伐木场), over almost the same time period.
The team found that elephants born in zoos lived an average of 16.9 years, but elephants that died of natural causes lived an average of 56 years. Asian elephants followed a similar pattern. In zoos, they lived 18.9 years, while those in the logging camp lived 41.7 years.
Scientists don’t yet know why wild elephants seem to live so much better than their zoo-raised counterparts (同类). Georgia Mason, a biologist at the University of Guelph in Canada, who led the study, thinks stress and obesity (肥胖) may be to blame. Zoo elephants don’t get the same kind of exercise they would in the wild. Elephants’ social lives are also much different in zoos than in the wild, where they live in large family groups.
小题1:Most people believe that________.

A．animals in zoos should live a longer life

B．zoos are not good for animals to live in

C．zoos are not suitable for large animals

D．captivity can affect animals in many ways

小题2:The purpose of the international scientists is_________.

A．to compare the lifespans of different animals

B．to find out how captivity affects elephants

C．to learn the lifespans of male and female elephants

D．to compare the lifespans of elephants in different places

小题3:Which elephants live the longest according to the study?

A．Elephants born in zoos.

B．Elephants that live in the wild.

C．Elephants that work in logging camps.

D．Female Asian elephants in logging camps.

小题4:We can infer from the passage that_________.

A．elephants in zoos suffer less stress than those in the wild

B．elephants in zoos live an easy life

C．social lives are not important to elephants

D．zoo life can be stressful to elephants

小题5:What are the advantages to elephants in the wild according to the passage?

A．They face fewer problems.	B．They can find food more easily.
C．They live in large social groups.	D．They are freer to move.