根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

It’s such a common event that you probably never asked yourself why you sleep.  ___1____ In fact, for sleep researchers, it’s one of the biggest unanswered questions in the field.

Stop and think about it for a second. Why should we sleep? ____2_____ But we sleep every night, even when we have had plenty of rest. There are，no doubt，several different answers to this question, but let’s just consider one general purpose of sleep: ____3_____ Human beings are creatures that are normally active during daylight hours, when our senses function most effectively.  ____4_____ We can’t see objects well, our color vision is entirely lost, and we don’t have the smelling or hearing sharpness of other animals.  So it actually does make sense to have us stay where we are during the dangerous period when night-waking animals are walking here and there. And one sure way to make sure we don’t fall down everywhere and get lost or eaten is to have us not move for seven or eight hours, rising again only when the light is back and our survival chances are better.

It’s not the only reason we sleep. ____5____Perhaps even the most important one.

A. Is it because we get tired?

B. Should that put human beings in a terrible situation?

C. But from a scientific point of view, this is far from an ordinary matter.

D. But in terms of evolution, it may have been one of the first reasons.

E. Furthermore, if you were designing an animal, would you have it come into long periods of unconsciousness every twenty-four hours? 

F. Sleep as a survival approach.

G. At night, humans do rather poorly.

 

　　完形填空:

　　He has been called the missing link half-man, half-breast．He is supposed to live in the highest mountain in the world Mount Everest．

　　He is known as the Abominable Snowman．The 　1　 of the Snowman has been around for 　2　 Climbers in the 1920s reported finding marks like those of human high up on the side of Mount Everest．The native people said they 　3　 this creature and called it the “Yeti” and they said that they had 　4　 caught Yetis on two occasions 　5　 none has ever been produced as evidence (证据)．

　　Over the years, the story of the Yetis has 　6　 In 1951, Eric Shipton took photographs of a set of tracks in the snow of Everest．Shipton believed that they were not 　7　 the tracks of a monkey or bear and 　8　 that the Abominable Snowman might really 　9　．

　　Further efforts have been made to find out about Yetis．But the only things people have ever found were 　10　 footprints．Most believe the footprints are nothing more than 　11　 animals tracks, which had been made 　12　 as they melted (融化) and refroze in the snow．　13　 , in 1964, a Russian scientist said that the Abominable Snowman was 　14　 and was a remaining link with the prehistory humans．But, 　15　 , no evidence has ever 　16　 been produced．

　　These days, only a few people continue to take the story of the Abominable snowman 　17　 ．But if they ever 　18　 catching one, they may face a real 　19　: would they put it in a 　20　 or give it a room in a hotel?

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He has been called the “missing link”.Half-man, half-beast. He is supposed to live in the highest mountain in the world—Mount Everest.

He is known as the Abominable Snowman. The   1  of Snowman has been around for

  2  .?Climbers in the 1920s reported finding marks like those of human feet high up on the side of Mount Everest. The native people said they  3  this creature and called it the “Yeti”,and they said that they had   4  caught Yetis on two occasions   5  none has ever been produced as evidence.

Over the years, the story of the Yetis has  6  . In 1916, Eric Shipton took photographs of a set of tracks in the snow of Everest. Shipton believed that they were not   7  the tracks of a monkey or bear and   8  that the Abominable Snowman might really   9  .

Further efforts have been made to find out about Yetis. But the only things people have ever found were   10  footprints. Most believe the footprints are nothing more than   11  animal tracks, which had been made  12  as they melted and refroze in the snow.  13  ,in 1964,a Russian scientist said that the Abominable Snowman was   14  and was a remaining link with the prehistoric humans. But,?  15  ,?no evidence has ever   16  been produced.

These days, only a few people continue to take the story of Abominable Snowman  17  ,?but if they ever   18  catching one, they may face a real  19  : Would they put it in a   20  or give it a room in a hotel?

1.A.event                            B.story                         C.adventure                  D.description

2.A.centuries                B.too long                    C.some time                 D.many years

3.A.heard from             B.cared for                   C.knew of                    D.read about

4.A.even                      B.hardly                       C.certainly                    D.probably

5.A.as                          B.though                      C.when                        D.until

6.A.developed               B.changed                    C.occurred                    D.continued

7.A.entirely                  B.naturally                   C.clearly                      D.simply

8.A.found                     B.declared                    C.felt                           D.doubted

9.A.exist                      B.escape                       C.disappear                   D.return

10.A.clearer                  B.more                         C.possible                     D.rare

11.A.huge                     B.recent                      C.ordinary                    D.frightening

12.A.strange                 B.large                         C.deep                         D.rough

13.A.In the end             B.Therefore                  C.After all                    D.However

14.A.imagined                     B.real                           C.special                      D.familiar

15.A.so                        B.besides                      C.again                        D.instead

16.A.rightly                  B.actually                     C.normally                   D.particularly

17.A.lightly                  B.jokingly                    C.seriously                   D.properly

18.A.succeed in             B.insist on                    C.depend on                 D.join in

19.A.decision                B.situation                    C.subject                      D.problem

20.A.zoo                      B.mountain                   C.museum                    D.laboratory

He has been called the "missing link." Half-man, half-beast. He is supposed to live in the highest mountain in the world-Mount Everest.

He is known as the Abominable Snowman. The 1of the Snowman has been around for 2

Climbers in the 1920s reported finding marks like those of human feet high up on the side of Mount Everest. The native people said they 3 this creature and called it the "Yeti," and they said that they had 4caught Yetis on two occasions 5 none has ever been produced as evidence（ 证据）.

Over the years, the story of the Yetis has 6 . In 1951, Eric Shipton took photographs of a set of tracks in the snow of Everest. Shipton believed that they were not 7 the tracks of a monkey or bear and 8that the Abominable Snowman might really 9.

Further efforts have been made to find out about Yetis. But the only things people have everfound were 10footprints. Most believe the footprints are nothing more than 11 animal tracks, which had been made 12 as they melted （融化） and refroze in the snow. 13 in 1964, a Russian scientist said that the Abominable Snowman was 14 and was a remaining link with the prehistoric humans. But,  15, no evidence has ever 16 been produced.

These days, only a few people continue to take the story of the Abominable Snowman 17 . But if they ever 18 catching one, they may face a real 19Would they put it in a 20 or give it a room in a hotel?

1 A. event                       B. story                     C. adventure              D. description

2 A. centuries                 B. too long                  C. some time             D. many years

3. A. heard from             B. cared for                C. knew of                D. read about

4.A. even                       B. hardly                    C. certainly                D. probably

5. A. as                          B. though                   C. when                    D. until

6.A.developed                 B. changed                 C. occurred               D. continued

7. A. entirely                   B. naturally                 C. clearly                  D. simply

8. A. found                     B. declared                 C. felt                       D. doubted

9. A. exist                       B. escape                   C. disappear              D. return

10.A.clearer                   B. more                      C. possible                D. rare

11. A. huge                     B. recent                    C. ordinary                D. frightening

12.A.strange                   B. large                      C. deep                     D. rough

13.A. In the end              B. Therefore               C. After all                 D. However

14. A. imagined               B. real                        C. special                  D. familiar

15. A. so                        B. besides                   C. again                    D. instead

16. A. rightly                  B. actually                  C. normally               D. particularly

17 A. lightly                    B. jokingly                  C. seriously               D. properly

18. A. succeed in            B. insist on                 C. depend on             D. join in

19. A. decision               B. situation                 C. subject                  D. problem

20. A. zoo                      B. mountain                C. museum         D. laboratory

He has been called the “missing link”. Half-man, half-beast. He is supposed to live in the highest mountain in the world — Mount Everest. He is known as the Abominable Snowman. The ___1___ of Snowman has been around for ___2___. Climbers in the 1920s reported finding marks like those of human feet high up on the side of Mount Everest. The native people said they ___3___ this creature and called it the “Yeti”, and they said that they had ___4___ caught Yetis on two occasions ___5___ none has ever been produced as evidence (证据).

Over the years, the story of the Yetis has ___6___. In 1951, Eric Shipton took photographs of a set of tracks in the snow of Everest. Shipton believed that they were not ___7___ the tracks of a monkey or bear and ___8___ that the Abominable Snowman might really ___9___.

Further efforts have been made to find out about Yetis. But the only things people have ever found were ___10___ footprints. Most believe the footprints are nothing more than ___11___ animal tracks, which had been made ___12___ as they melted(融化) and refroze in the snow. ___13___, in 1964, a Russian scientist said that the Abominable Snowman was ___14___ and was a remaining link with the prehistoric humans. But, ___15___, no evidence has ever ___16___ been produced.

These days, only a few people continue to take the story of the Abominable Snowman ___17___, but if they ever ___18___ catching one, they may face a real ___19___: Would they put it in a ___20___ or give it a room in a hotel?

1. A. event     B. story   C. adventure   D. description

2. A. centuries       B. too long     C. some time  D. many years

3. A. heard from    B. cared for    C. knew of     D. read about

4. A. even      B. hardly C. certainly     D. probably

5. A. as   B. though       C. when  D. until

6. A. developed      B. changed     C. occurred     D. continued

7. A. entirely  B. naturally    C. clearly       D. simply

8. A. found     B. declared     C. felt     D. doubled

9. A. exist      B. escape C. disappear    D. return

10. A. clearer  B. more   C. possible      D. rare

11. A. huge     B. recent C. ordinary     D. frightening

12. A. strange B. large   C. deep   D. rough

13. A. In the end    B. Therefore   C. After all     D. However

14. A. imagined     B. real     C. special       D. familiar

15. A. so B. besides       C. again  D. instead

16. A. rightly  B. actually      C. normally    D. particularly

17. A. lightly  B. jokingly     C. seriously    D. properly

18. A. succeed in    B. insist on     C. depend on  D. join in

19. A. decision       B. situation     C. subject       D. problem

20. A. zoo      B. mountain    C. museum     D. laboratory