Judging from recent surveys,most experts in sleep behavior agree that there is virtually an epidemic of sleepiness in the nation. I cantthink of a single study that hasnt found Americans getting less sleep thanthey ought to, says Dr. David. Even people who think they are sleeping enoughwould probably be better off with more rest.

　　The beginning of our sleep-deficit crisis can betraced to the invention of the light bulb a century ago. From diary entries andother personal accounts from the 18th and 19th centuries, sleep scientists havereached the conclusion that the average person used to sleep about 9.5 hours anight. The best sleep habits once were forced on us, when we had nothing to doin the evening down on the farm, and it was dark. By the 1950s and 1960s, thatsleep schedule had been reduced dramatically, to between 7.5 and eight hours,and most people had to wake to an alarm clock. People cheat on their sleep,and they dont even realize theyre doing it, says Dr. David. They thinktheyre okay because they can get by on 6.5hours, when they really need 7.5, eight or even more to feel ideallyvigorous.

　　Perhaps the most merciless robber of sleep,researchers say, is the complexity of the day. Whenever pressures from work,family, friends and community mount, many people consider sleep the leastexpensive item on his programme. In our society, youre considered dynamic ifyou say you only need 5.5 hours sleep. If youve got to get 8.5 hours, peoplethink you lack drive and ambition.

　　To determine the consequences of sleep deficit,researchers have put subjects through a set of psychological and performancetests requiring them, for instance, to add columns of numbers or recall apassage read to them only minutes earlier. Weve found that if youre insleep deficit, performance suffers, says Dr. David. Short-term memory isweakened, as are abilities to make decisions and to concentrate.

　　1. People in the 18th and 19th centuries used to sleep about 9.5 hoursa night because they

　　had _______ .

　　A) no drive and ambition B) noelectric lighting

　　C) the best sleep habits D)nothing to do in the evening

　　2. According to Dr. David, Americans _______ .

　　A) areideally vigorous even under the pressure of life

　　B) ofienneglect the consequences of sleep deficit

　　C) do notknow how to relax themselves properly

　　D) can getby on 6.5 hours of sleep

　　3. Many Americans believe that _______ .

　　A) sleep isthe first thing that can be sacrificed when one is busy

　　B) they needmore sleep to cope with the complexities of everyday life

　　C) to sleepis something one can do at any time of the day

　　D) enoughsleep promotes peoples drive and ambition

　　4. The word subjects refers to______ .

　　A) the performancetests used in the study of sleep deficit

　　B) specialbranches of knowledge that are being studied

　　C) peoplewhose behavior or reactions are being studied

　　D) thepsychological consequences of sleep deficit

　　5. It can be concluded fromthe passage that one should sleep as many hours as is necessary to ______ .

　　A) improveones memory dramatically

　　B) beconsidered dynamic by other people

　　C) maintainones daily schedule

　　D) feelenergetic and perform adequately

　　1.B答案見第2段第1句。18、19世紀的時候，首先是因為沒有電燈照明，所以人們晚上才無事可做，只好早早睡覺。而不是D項所說，是由于無事可做才多睡。

　　2.B全篇多處提到Dr.David的看法，在文中找到有Dr.David說話的地方，綜合比較一下，不難看出Dr.David認為美國人經常忽視睡眠不足的后果。

　　3.A答案見第2段倒數第1、2句和第3段第1、2句。

　　4.C最后一段一開始就講，為了確定睡眠不足所產生的后果，研究人員讓subjects通過一系列心理和行為的測試，要求他們把一欄數字相加或者回憶剛讀過的文章。這樣看來，subjects應該是指人了。

　　5.D推理題，依據見本文最后兩句話。其實，也只有D項才把睡眠充足所帶來的好處講得最完整。

　　Judging from recent surveys,most experts in sleep behavior agree that there is virtually an epidemic of sleepiness in the nation. I cantthink of a single study that hasnt found Americans getting less sleep thanthey ought to, says Dr. David. Even people who think they are sleeping enoughwould probably be better off with more rest.

　　The beginning of our sleep-deficit crisis can betraced to the invention of the light bulb a century ago. From diary entries andother personal accounts from the 18th and 19th centuries, sleep scientists havereached the conclusion that the average person used to sleep about 9.5 hours anight. The best sleep habits once were forced on us, when we had nothing to doin the evening down on the farm, and it was dark. By the 1950s and 1960s, thatsleep schedule had been reduced dramatically, to between 7.5 and eight hours,and most people had to wake to an alarm clock. People cheat on their sleep,and they dont even realize theyre doing it, says Dr. David. They thinktheyre okay because they can get by on 6.5hours, when they really need 7.5, eight or even more to feel ideallyvigorous.

　　Perhaps the most merciless robber of sleep,researchers say, is the complexity of the day. Whenever pressures from work,family, friends and community mount, many people consider sleep the leastexpensive item on his programme. In our society, youre considered dynamic ifyou say you only need 5.5 hours sleep. If youve got to get 8.5 hours, peoplethink you lack drive and ambition.

　　To determine the consequences of sleep deficit,researchers have put subjects through a set of psychological and performancetests requiring them, for instance, to add columns of numbers or recall apassage read to them only minutes earlier. Weve found that if youre insleep deficit, performance suffers, says Dr. David. Short-term memory isweakened, as are abilities to make decisions and to concentrate.

　　1. People in the 18th and 19th centuries used to sleep about 9.5 hoursa night because they

　　had _______ .

　　A) no drive and ambition B) noelectric lighting

　　C) the best sleep habits D)nothing to do in the evening

　　2. According to Dr. David, Americans _______ .

　　A) areideally vigorous even under the pressure of life

　　B) ofienneglect the consequences of sleep deficit

　　C) do notknow how to relax themselves properly

　　D) can getby on 6.5 hours of sleep

　　3. Many Americans believe that _______ .

　　A) sleep isthe first thing that can be sacrificed when one is busy

　　B) they needmore sleep to cope with the complexities of everyday life

　　C) to sleepis something one can do at any time of the day

　　D) enoughsleep promotes peoples drive and ambition

　　4. The word subjects refers to______ .

　　A) the performancetests used in the study of sleep deficit

　　B) specialbranches of knowledge that are being studied

　　C) peoplewhose behavior or reactions are being studied

　　D) thepsychological consequences of sleep deficit

　　5. It can be concluded fromthe passage that one should sleep as many hours as is necessary to ______ .

　　A) improveones memory dramatically

　　B) beconsidered dynamic by other people

　　C) maintainones daily schedule

　　D) feelenergetic and perform adequately

　　1.B答案見第2段第1句。18、19世紀的時候，首先是因為沒有電燈照明，所以人們晚上才無事可做，只好早早睡覺。而不是D項所說，是由于無事可做才多睡。

　　2.B全篇多處提到Dr.David的看法，在文中找到有Dr.David說話的地方，綜合比較一下，不難看出Dr.David認為美國人經常忽視睡眠不足的后果。

　　3.A答案見第2段倒數第1、2句和第3段第1、2句。

　　4.C最后一段一開始就講，為了確定睡眠不足所產生的后果，研究人員讓subjects通過一系列心理和行為的測試，要求他們把一欄數字相加或者回憶剛讀過的文章。這樣看來，subjects應該是指人了。

　　5.D推理題，依據見本文最后兩句話。其實，也只有D項才把睡眠充足所帶來的好處講得最完整。