单项选择题
Taking a Nap During the Day
Medical experts say most Americans do not get enough sleep. They say more Americans need to(51) for a short period in the middle of the day. They are advising people to sleep lightly(52) continuing with other activities.
One study earlier this year found that persons who sleep for a few minutes during the day were less likely to die of (53) disease. The study followed more than 2,300 Greek adults (54) about six years. Adults who rested for half an hour at least three times a week had a 37 percent lower(55) of dying from heart disease than those who did not nap.
Study organizers said the strongest (56) was in working men. They said naps might improve health by mitigating (减低) tension (57) by work.
Some European and Latin American businesses have Supported the idea of (58) for many gears. They urge(催促)people to (59) work,go home and have a nap before returning. In the United States, some companies let workers rest briefly in their offices. They believe this reduces mistakes and accidents,and also (60) the amount of work a person can do.
Sleep experts say it is likely that people (61) more mistakes at work than at other times. They say people should not carry out important duties (62) they feel sleepy. And they say the ]rest thing to do is to take a nap. About twenty minutes of rest is all you (63) . Experts say this provides extra energy and can increase your (64) until the end of the day. But experts (65) that a nap should last no more than twenty to thirty minutes. A longer nap will put the body into deep sleep and waking up will be difficult.
A．when
B．until
C．although
D．and