完形填空In North America,the number of people who work for 10-12

完形填空
In North America,the number of people who work for 10-12 hours a day is increasing.More people are working night shifts( 夜班),from 11 PM (51)________ 7 AM.But most adults need about 7-10 hours of sleep a day.On (52)________ ,North Americans are only getting about 6-8 hours of sleep.In fact,over the past century,North Americans have reduced the number of nightly sleeping hours by about twenty percent.These lost hours of sleep have been (53)________ mainly by work and work-related activities.
Some exports are worried that tired workers are becoming a danger in the workplace.A tired worker is (54)________ to forget important information and make mistakes.Mistakes can (55)________ to serious work accidents.Tiredness has been linked either (56)________ or indirectly to some of the worst accidents in history.Allowing workers to nap could be a (57)________ response(回应) to the problem.Studies have also shown that an afternoon nap(小睡、打盹) can significantly(58)________ mental abilities and improve mood.Research into allowing people in the airline industry to take short naps is (59)________ some interesting results.Researchers at NASA have studied the (60)________ of taking forty-minute naps for pilots on overseas international flights.They found that when pilots napped,they were more alert afterward and could function better.
51.A.until B.to C.from D.for
52.A.special B.abnormal C.normal D.average
53.A.replace B.replaced C.to replace D.replacing
54.A.like B.liking C.likely D.unlikely
55.A.leading B.to lead C.leaded D.lead
56.A.directly B.indirectly C.direct D.indirectly
57.A.helpful B.helpless C.help D.helping
58.A.increases B.increasing C.increase D.to increase
59.A.produce B.produced C.producing D.to produce
60.A.effect B.effects C.affect D.affects

BDBCD DACCA
第56题DB两个选项一样