阅读下面短文，掌握其大意，然后从各题所给的四个选项（A、B、C和D）中，选出最佳选项，并在答题卡上将该项涂黑。
At the beginning of this century, medical scientists made an interesting discovery: we are built not just of flesh(肌肉) and blood but also of time. They were 1to show that we all have a ‘body clock’ 2us, which controls the 3and fall of our body energies, 4us different from one day to the next.
The 5of a ‘body clock’ should not be too 6since the lives of most living things are controlled 7the 24-hour night-and-day cycle(循环). We feel 8and fall asleep at night and become 9and energetic during the day. If the 24-hour cycle is 10most people experience unpleasant 11. For example, people who are not 12to working at night can find that 13of sleep causes them to 14badly at work.
15the daily cycle of sleeping and 16, we also have other cycles which 17longer than one day. Most of us would 18that we feel good on some days and not so good on 19; sometimes our ideas seem to flow and at other times, they 20do not exist.
1.A. anxious B. careful C. able D. proud
2.A. around B. inside C. between D. on
3.A. rise B. supply C. use D. movement
4.A. showing B. treating C. changing D. making
5.A. idea B. opinion C. story D. invention
6.A. difficult B. exciting C. interesting D. surprising
7.A. from B. over C. by D. during
8.A. dull B. dreamy C. tired D. peaceful
9.A. regular B. excited C. clear D. lively
10.A. shortened B. disturbed C. reset D. troubled
11.A. moments B. senses C. feelings D. effects
12.A. used B. allowed C. expected D. prevented
13.A. miss B. none C. need D. lack
14.A. show B. perform C. manage D. control
15.A. With B. Except C. As well as D. Rather than
16.A. waking B. moving C. living D. working
17.A. repeat B. remain C. happen D. last
18.A. believe B. agree C. realize D. allow
19.A. others B. the other C. all other D. other
20.A. only B. just C. still D. yet
---I’m afraid that Mr. Wood can’t see you until 4 o’clock.
---Oh, ______ I won’t wait.
A. no doubt B. after all C. in that case D. in this way
Little ______ about her own safety, though she was in great danger herself.
A. did Rose care B. Rose did care C. Rose does care D. does Rose care
______ to reach them on the phone, we sent an email instead.
A. Fail B. Failed C. To fail D. Having failed
Our bodies are strengthened by taking exercise. ______, our minds are developed by learning.
A. Probably B. Likely C. Similarly D. Generally
American Indians ______ about five percent of the U.S. population.
A. fill up B. bring up C. set up D. make up
