共用题干第三篇
Longer Lives for Wild Elephants
Most people think of zoos as safe places for animals,where struggles such as having difficulty finding
food and avoiding predators（猛兽）don't exist. Without such problems,animals in zoos should live to a ripe
（成熟的）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.Sometimes,they even become unable to have babies.
To learn more about how captivity（圈养）affects elephants, a team of international scientists compared
the life spans of female elephants born in zoos with female elephants living outdoors in their native lands.
Zoos keep detailed records of all the animals in their care,documenting factors such as birth dates,illnes-
ses,weight and death.These records made it possible for the researchers to analyze 40 years of data on 800
African and Asian elephants in zoos across Europe.The scientists compared the life spans of the zoo-born fe-
male elephants with the life spans of thousands of wild female elephants in Africa and Asian elephants that
work in logging camps（伐木场）, over approximately the same time period.
The team found that female African elephants born in zoos lived an average of 16.9 years. Their wild
counterparts who died of natural causes lived an average of 56 years一more than three times as long. Female
Asian elephants followed a similar pattern. In zoos,they lived 18.9 years,while those in the logging camps
lived 41.7 years.
Scientists don't know yet why wild elephants seem to get on so much better than their zoo-raised coun-
terparts.Georgia Mason,a biologist at the University of Guelph in Canada who led the study,thinks stress
and obesity（肥胖症）may be to blame. Zoo elephants don't get the same kind of exercise they would in the
wild,and most are very fat. Social lives of elephants are also much different in zoos than in the wild,where
they live in large herds and family groups.
The study raises some questions about acquiring more elephants to keep in zoos.While some threatened
and endangered species living in zoos reproduce（生殖）successfully and maintain healthy populations,that
doesn't appear to be the case with elephants. It can be inferred from the last paragraph that______________.A:zoo-born elephants should be looked after more carefullyB:zoos should keep more animals except elephantsC:it may not be wise to keep elephants in zoosD:elephants are no longer an endangered species

相关标签： 伐木场   肥胖症