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         to show that we all have “a body clock”          us, which controls the         and fall of our body energies,         us different from one day to the next.
The         of “a body clock” should not be too         since the lives of most living things are controlled         the 24 hour night-and-day cycle. We feel         and fall asleep at night and become         and energetic during the day. If the 24 hour-cycle is         , most people experience unpleasant         . For example, people who are not         to working at night can find that         of sleep causes them to         badly at work.
       the daily cycle of sleeping and        , we also have other cycles which        longer than one day. Most of us would         that we feel good on some days and not so good on         ; sometimes our ideas seem to flow and at other times, they         do not exist.

A．anxious B．able C．careful D．proud

A．inside B．around C．between D．on

A．movement B．supply C．use D．rise

A．showing B．treating C．making D．changing

A．invention B．opinion C．story D．idea

A．difficult B．exciting C．surprising D．interesting

A．from B．by C．over D．during

A．dull B．tired C．dreamy D．peaceful

A．regular B．excited C．lively D．clear

A．disturbed B．shortened C．reset D．troubled

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．working B．moving C．living D．waking

A．repeat B．remain C．last D．happen

A．agree B．believe C．realize D．allow

A．other B．the other C．all other D．others

A．just B．only C．still D．yet