At the beginning of this century, medical scientists made an interesting discovery; we are built not just of flesh and blood but also of time. They were able to show that we all have "a body clock" 36 us, which controls the rise and fall of our body energies, 37 us different from one day to the next.
The idea of "a body clock" should not be too 38 since the lives of most living things are controlled by the 24 hour night-and-day cycle. We feel 39 and fall asleep at night and become 40 and energetic during the day. If the 24 hour-cycle is disturbed, most people experience unpleasant 41 . For example, people who are not 42 to working at night can find that 43 of sleep causes them to 44 badly at work. 45 the daily cycle of sleeping and waking, we also have other cycles which last longer than one day. Most of us would 46 that we feel good on some days and not so good on others ; sometimes our ideas seem to flow and at other times, they 47 do not exist.
A.inside B.around C.between D.on
A.showing B.treating C.making D.changing
A.difficult B.exciting C.surprising D.interesting
A.dull B.tired C.dreamy D.peaceful
A.regular B.excited C.lively D.clear
A.moments B.feelings C.senses D.effects
A.prevented B.allowed C.expected D.used
A.miss B.none C.lack D.need
A.perform B.show C.manage D.control
A.With B.As well as C.Except D.Rather than
A.agree B.believe C.realize D.allow
A.just B.only C.still D.yet