完形填空

　　The skill in being a student consists in getting one's daily study as near the optimum(最佳的) point as possible. It differs with the 1 of work, it differs from person to person, and even in the 2 person it varies from week to week. You must 3 to find your own. Every day you study, 4 this principle (原理) of the optimum in mind. When you feel yourself getting tired, if you find yourself 5 reading over the same paragraph and not taking it 6 , that's a pretty good sign you've reached the top for the day and should stop. Most ordinary students find their optimum at about five hours a day. 7 may be a little more or a little less— but if you 8 five hours' good work a day, you'll be doing well .

　　 9 , what are you doing with yourself when you are not working? Before exams some students do 10 at all except sit in a chair and worry. Here is another misunderstanding. People too easily think of the mind 11 it worked like the 12 , it doesn't. If one want to keep physical energy to cut a large amount of firewood, one would 13 flat on a bed and rest when one wasn't cutting. But the 14 cannot rest. Even in sleep you dream, even if you forget your dreams. The mind is always turning. It gets its 15 only by variety. That is what makes mental 16 .

　　When you've finished your 17 hours, you must not sit in the chair thinking about the work —- that only 18 without any learning. You must get out and do something. It doesn't matter 19 — anything as long as you are 20 doing something else but work.

1．

[　　]

2．

[　　]

3．

[　　]

4．

[　　]

5．

[　　]

6．

[　　]

7．

[　　]

8．

[　　]

9．

[　　]

10．

[　　]

11．

[　　]

12．

[　　]

13．

[　　]

14．

[　　]

15．

[　　]

16．

[　　]

17．

[　　]

18．

[　　]

19．

[　　]

20．

[　　]