题目内容：

    Bats are the only mammals 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 live so 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 the bats’ chromosomes (染色体), a line of genes found in the nucleus 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 break down. They say this is what cause 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 the oldest age, reaching 41 years. The scientists’ findings suggest that these bats’ cells have the ability to maintain and repair their telomeres. This 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.Why are European researchers studying bats?

A.To learn the similar habits between bats and human beings.

B.To find out why the greater mouse-eared bats live a long life.

C.To try to understand why bats prefer to fly during the night.

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

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

A.The structures of the bats’ chromosomes. B.What causes aging biologically.

C.The functions of telomeres. D.What causes cells to break down.

3.Why do the greater mouse-eared bat and another Myotis bat live so long?

A.They are grouped together under the name Myotis.

B.Their telomeres are decreasing with age.

C.Their cells are able to keep up and fix their telomeres.

D.They have more telomeres than human beings do.

4.What can we infer from the last paragraph?

A.Bats live 10 times longer than other mammals.

B.Bats enjoy the longest life among mammals.

C.The greater mouse-eared bat and other bats should have lived longer.

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