题目内容：

Research suggests that a newly-identified gene known as insomniacs(失眠症患者) may play a role in keeping us asleep. By cloning and testing this gene in about 21,000 fruit flies, Rockefeller University researchers say they have discovered an entirely new mechanism (机制) by which sleep is controlled.

By studying these flies, the researchers discovered that mutations(变异) in the insomniac gene were associated with a great reduction in sleep. While a typical fruit fly slept for an average of 927 minutes a day, the mutant flies slept for just 317. They also slept for shorter periods of time, and slept and woke more frequently.

“The results showed a great loss of both the time that the flies’ sleep lasted and their ability to remain asleep after they slept,” says researcher Nicholas Stavropoulos.

The researchers also examined the link between sleep and lifespan, finding that flies with mutations to the insomniac gene lived only about two-thirds as long as unchanged flies. But when the scientists removed insomniac only in neurons（神经细胞）---allowing it to remain in the rest of the flies’ bodies---this difference disappeared; the resulting animals slept poorly but lived just as long.

“This suggests that reduced sleep can be ‘uncoupled’(分开) from reduced lifespan, supporting the idea that some interruptions of sleep do not affect overall health, at least as far as lifespan is concerned,” Stavropoulos says.

Although flies and humans would appear to have little in common when it comes to lifestyle, scientists say that the mechanisms of sleep and wakefulness are likely to be quite similar.

“Sleep is a fundamental behavior in all animals, and it is poorly understood from a scientific standpoint, says Stavropoulos. This work could prove useful in understanding and treating sleep disorders”

1.The text is mainly about____.

A．the progress in cloning fruit flies

B．the methods of cloning fruit flies

C．the link between gene and lifespan

D．the influence of a gene on the ability to sleep

2.According to paragraph2, the mutant flies________.

A．slept about 5 hours a day

B．had problems waking up

C．didn’t seem sleepy at all

D．could not fall asleep

3.We can conclude from the text that________.

A．sleep and health go hand in hand

B．sleep can be controlled by humans

C．research into sleep is very fruitful

D．the findings are useful in medical treatment