Medical experts say most Americans do not get {{U}}(51) {{/U}}
sleep. They say more Americans need to rest for a short period in the middle of
the day. They are advising people to sleep lightly before {{U}}(52)
{{/U}} with other activities. One study earlier this year
found that persons who sleep for a few minutes during the day were less
{{U}}(53) {{/U}} to die of disease. The study followed more than 2,300
Greek adults {{U}}(54) {{/U}} about six years. Adult who rested for half
an hour {{U}}(55) {{/U}} three times a week had a 37 percent lower risk
of dying from heart disease than those who did not nap. Study
organizers said the strongest evidence was in working men. They said naps might
improve {{U}}(56) {{/U}} by mitigating tension caused by work.
Some European and Latin American businesses have supported the
{{U}}(57) {{/U}} of napping for many years. They urge people to
{{U}}(58) {{/U}} 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 {{U}}(59) {{/U}} and accidents, and {{U}}(60)
{{/U}} increases the amount of work a person can do. Sleep
experts say it is likely that people make more mistakes at work than at other
times. They say people should not carry out important duties when they feel
{{U}}(61) {{/U}}. And they say the best thing to do is to take a nap.
About twenty minutes of rest is {{U}}(62) {{/U}} you need. Experts say
this provides extra energy and can increase your effectiveness {{U}}(63)
{{/U}} the end of the day. But experts warn that a nap {{U}}(64)
{{/U}} last no more than twenty to thirty minutes. A longer nap will put the
body into deep sleep and waking up will be {{U}}(65)
{{/U}}.
【正确答案】
D
【答案解析】[解析] 本段第二句说“more Americans need to rest for a short period in the middle of the day”，引导我们选择(not)enough。因为睡眠不够，才要中午“打个盹”。B与上下文意思不符，因为文章没有提到中午打盹的原因是晚上没有睡好。
【答案解析】[解析] 前半句说“people should not carry out important duties…”，后半句自然会想到“when they feel sleepy”。而when they feel ready/good/awake都说不通。
【正确答案】
A
【答案解析】[解析] 本句的意思是：大约20分钟的打盹是你所需要的。所以，只有“About twenty minutes of rest is all you need”才说得通。
【正确答案】
C
【答案解析】[解析] 前半句说“this(指打盹)provides extra energy and can increase your effectiveness”，后面接“while unless during the end of the day”不搭配，只有until(the end of the day)才是正确答案。