leep is something we generally associate with (11)___ creatures. Of course, it is true that a lot of animals sleep, but zoologists are not certain that primitive forms of animal (12)___ like worms and snails, ever really (13)___. (14)___ the other hand, animals such as bears sleep for 4 or 5 months every year.

　　The amount of sleep (15)___ human being needs depends (16)___, the individual and possibly race. For example, doctors think that pre-school children need between 10 and 12 hours a night; school children between 9 and 11 hours; and adults between 7 and 9 hours. There are exceptional cases of old people (17)___ only sleep between 2 and 3 hours a day and (18)___ to be active and healthy. The sleep requirements of different (19)___ also appear to be different. Japanese people, for example, sleep (20)___ hours than Europeans.

　　11. A. live B. living C. lively D. alive

　　12. A. life B. lives C. lifes D. living

　　13. A. sleep B. sleeps C. sleeping D. slept

　　14. A. In B. At C. On D. For

　　15. A. the B. / C. a D. an

　　16. A. on age B. on the age C. in age D. for age

　　17. A. that they B. which C. of whom D. who

　　18. A. continued B. continue C. went on D. going

　　19. A. race B. human being C. man D. races

　　20. A. less B. by far less C. fewer D. much more

　　答案： 1. D 2. B 3. C 4. B 5. C 6. B 7. B 8. D 9. A 10. C

　　11. B 12. A 13. A 14. C 15. C 16. A 17. D 18. B 19. D 20. C