阅读理解。
Longer Lives for Wild Elephants
Most people think of zoos as safe places for animals, where struggles such as difficulty finding food and avoiding predators 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 suffer from poor health. They 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 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,
illnesses, 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 elephants with the life spans of thousands of female wild 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--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 yet know why wild elephants seem to live so much better than their zoo-raised counterparts. 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, and most are very fat. Elephant social lives are also much different in zoos than in the wild, where they live in large herds and family groups.
Another finding from the study showed that Asian elephants born in zoos were more likely to die early
than Asian 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 maintain healthy populations, that
doesn't appear to be the case with elephants.
1. According to the first two paragraphs, unlike other zoo animals, zoo elephants _______ .
A. have difficulty eating food.
B. 1ive to a ripe old age.
C. are not afraid of predators.
D. develop health problems.
2. Which of the following about the international scientists' research on the life spans of elephants is
NOT true? (See paragraph 3)?
A. They compared zoo elephants with wild elephants.
B. They kept detailed records of all the elephants in their care.
C. They analyzed the records of the elephants kept in zoos.
D. The zoo-born elephants they studied are kept in European zoos.
3. What do the scientists find in their research?
A. Female elephants live longer than male elephants.
B. Female zoo elephants live longer than their wild counterparts.
C. Female zoo elephants die much earlier than their wild counterparts.
D. Elephants in zoos and those in the wild enjoy the same long life spans.
4. Which of the following does the author suggest in the last paragraph?
A. It may not be a wise policy to keep elephants in the zoo.
B. Elephants are no longer an endangered species.
C. Zoo-born elephants should be looked after more carefully.
D. Zoos should keep more animals except elephants.
