| 完形填空。 | ||||
| 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 1 to show that we all have a 'body clock' 2 us, which controls the 3 and fall of our body energies, 4 us different from one day to the next. The 5 of a 'body clock' should not be too 6 since the lives of most living things are controlled 7 the 24-hour night-and-day cycle (循环). We fell 8 and fall asleep at night and become 9 and energetic during the day. If the 24-hour cycle is 10 most people experience unpleasant 11 , For example, people who are not 12 to working at night can find that 13 of sleep causes them to 14 badly at work. 15 the daily cycle of sleeping and 16 , we also have other cycle which 17 longer than one day. Most of us would 18 that we feel good on some days and not so good on 19 ; sometimes our ideas seem to flow and at other times, the 20 do not exist. | ||||
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