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   36   to show that we all have “a body clock”   37    us, which controls the   38   and fall of our body energies,   39   us different from one day one to the next.
The   40   of “a body clock” should not be too   41   since the lives of most living things are controlled   42   the 24 hour night-and-day cycle. We feel   43   and fall asleep at night and become   44   and energetic during the day. If the 24 hour-cycle is   45   , most people experience unpleasant   46   . For example, people who are not   47   to working at night can find that   48   of sleep causes them to   49   badly at work.
50   the daily cycle of sleeping and   51  , we also have other cycles which   52   longer than one day. Most of us would   53   that we feel good on some days and not so good on    54   ; sometimes our ideas seem to flow and at other times, they   55   do not exist.
36．A．anxious                 B．able                        C．careful                    D．proud
37．A．inside                     B．around                    C．between                  D．on
38．A．movement                     B．supply                    C．use                         D．rise
39．A．showing                 B．treating                   C．making                   D．changing
40．A．invention                B．opinion                   C．story                      D．idea
41．A．difficult                  B．exciting                  C．surprising               D．interesting
42．A．from                      B．by                          C．over                       D．during
43．A．dull                       B．tired                             C．dreamy                  D．peaceful
44．A．regular                   B．excited                   C．lively                            D．clear
45．A．disturbed                B．shortened                C．reset                       D．troubled
46．A．moments                B．feelings                  C．senses                     D．effects
47．A．prevented               B．allowed                  C．expected                 D．used
48．A．miss                       B．none                       C．lack                        D．need
49．A．perform                  B．show                      C．manage                   D．control
50．A．With                      B．As well as               C．Except                    D．Rather than
51．A．working                 B．moving                   C．living                     D．waking
52．A．repeat                     B．remain                   C．last                         D．happen
53．A．agree                      B．believe                   C．realize                    D．allow
54．A．other                      B．the other                 C．all other                  D．others
55．A．just                        B．only                       C．still                        D．yet