题目内容：

Bats are the only mammals(哺乳动物) that can fly a great distance, but they have another ability. Many bats live a very long time for an animal of their size. European researchers are studying bats to understand why they lives0 long. They hope to make discoveries aimed at fighting the aging process in human beings.

Last week, the group of scientists said they had identified important biological qualities in some bat species. The group studied bat chromosomes(染色体), a line of genes found in the nucleus(细胞核) of cells. The scientists were most interested in structures connected to the ends of the chromosomes. They are called telomeres(端粒), which protect the ends of chromosomes and shorten each time a cell divides. Scientists believe this shortening process causes cells to breakdown. They say this is what causes aging.

The European researchers studied 493 bats from four bat species. The group used information that had been gathered over more than 60 years. Of these animals ，the greater mouse-eared bat generally lived the longest, an average of 37 years. The scientists said this and a related species, which are grouped together under the name Myotis, had telomeres that did not shorten with age. Another Myotis bat holds the record for oldest age, reaching 41years. The scientists’ findings suggest that these bats cells have the ability to maintain and repair their telomeres. This, they said, helps guard against the aging process.

Based on its body size, a bat like the greater mouse-eared bat would be expected to live four years. But, these mammals have been found to live nearly 10 times longer than that. The scientists found that only 19 species of mammals live longer than humans when their body size is considered. Eighteen of these are bats.

1.European researchers are studying bats mainly hoping to             .

A. learn the living habit of bats.

B. find out why bats enjoy a long life.

C. try to understand why bats can fly as a mammal

D. discover a good way to prevent human beings from aging.

2.What does the second paragraph mainly explain to us?

A. The structures of bats’ chromosomes.

B. What cause aging biologically.

C. The functions of telomeres.

D. What causes cells to break down.

3.The greater mouse-eared bat and Myotis bat live so long because             .

A. they are grouped together under the name Myois

B. their telomeres are decreasing with age

C. their ells are able to keep up and fix their telomeres

D. their bodies produce more telomeres than human beings

4.From the last paragraph, we can infer that.             .

A. bats live 10 times longer that human beings

B. bats enjoy the longest life among mammals

C. bats like the greater mouse-eared bat should have lived longer

D. Most bats live longer than human beings considering their body size