Directions: There are 20 blanks in the following passage.
For each blank there are four choices marked A), B), C) and D) on the right side
of the paper. You should choose the ONE that best fits into the passage. Then
mark the corresponding letter on the Answer Sheet 2 with a single line through
the centre. Judging from recent surveys,
most experts in sleep behavior agree that there is virtually an epidemic (流行病)
of sleepiness in the nation. "I can’t think of a single study that hasn’t found
Americans 1 less sleep than they ought
to," says Dr. David. Even people who think they are sleeping enough would
probably be better off 2 more
rest. The beginning of our sleep-deficit (睡眠不足) crisis
can be 3 to the invention of the light
bulb a century ago. From diary entries and other personal
4 from the 18th and 19th centuries,
sleep scientists have 5 that the
average person used to sleep 9.5 hours a night. "The best sleep habits once were
forced on us, 6 we had nothing to do in
the evening down on the farm, and it was dark." By the 1950s and 1960s, that
sleep schedule 7 dramatically, to
between 7.5 and 8 hours, and 8 people
had to wake to an alarm clock. "People cheat on their sleep,
9 they don’t even realize they’re doing it," says Dr.
David, " They think they’re okay because they can 10 on 6.5 hours, when they really need 7.5, 8 or
even more to feel 11 vigorous. Perhaps the most merciless robber of sleep,
researchers say, is the complexity of the day. Whenever
12 from work, family, friends and community mount (上升),
many people consider sleep the least 13 item on his program. "In our society, you 14
dynamic if you say you only need 5.5 hours’ sleep. If you’ve got
to get 8.5 hours, people think you 15 drive and ambition. " To determine the 16 of sleep deficit, researchers have put
subjects through a set of psychological and performance tests 17 them, for instance, to add columns of numbers
or 18 a passage read to them only
minutes earlier. "We’ve found that if you’re in sleep deficit, performance
19 ," says Dr. David, " Short-term
memory is weakened, 20 are abilities to
make decisions and to concentrate. "