单项选择题
| Scientists are learning more about our
need for sleep. Most people sleep (26) eight hours each
night. (27) people sleep more than (28)
and others sleep as (29) as two or three hours each
night. Scientists do not know exactly (30) some people sleep
more than others. Dr. Ernest Hartman has a (an) (31) about
this. He believes that the (32) of sleep depends on how a
person (33) problems. He said people who need only a few
(34) sleep usually are people who have much energy and make good
use of (35) to get their work to be done quickly.
(36) he said many people who sleep longer than normal do
creative work and seem to need (37) dreaming time to find
solution (38) emotional problems. Some scientists agree
(39) this idea and others dispute. To determine the (40) of the lack of sleep, scientists have put (41) through a set of psychological and performance tests (42) them, for instance, to add columns of numbers or recite a passage read to them only minutes earlier, "We’ve found that if you’re in sleep (43) , performance suffers," says Dr. David. "Short-term memory is (44) , (45) are abilities to make decisions and to concentrate." |