A Biological Clock Every living thing has what scientists call a biological clock that controls behavior. The biological clock tells _____1___ when to form flowers and when the flowers should open1. It tells _____2____ when to leave the protective cocoon and fly away, and it tells animals and human beings when to eat, sleep and wake./ [" b$ u+ s# I! r2 r6 ~
Events outside the plant and animal _____3_____ the actions of some biological clocks. Scientists recently found, for example, that a tiny animal changes the color of its fur ____4_____ the number of hours of daylight. In the short ____5___ of winter, its fur becomes white. The fur becomes gray brown in color in the longer hours of daylight summer.
$ E7 ~. d6 c" ` Inner signals control other biological clocks. German scientists found that some kind of internal clock seems to order birds to begin their long migration _____6____ twice each year. Birds _____7_____ flying become restless when it is time for the trip, ____8___ they become calm again when the time of the flight has ended.
- i7 f$ g4 Z, g Scientists say they are beginning to learn which ____9____ of the brain contain biological clocks. An American researcher, Martin Moorhead, said a small group of cells near the front of the brain ____10____ to control the timing of some of our actions. These ____11____ tell a person when to _____12_____, when to sleep and when to seek food. Scientists say there probably are other biological clock cells that control other body activities./ d6 I( D) |9 ?7 e5 }: Z
Dr. Moorhead is studying _____13____ our biological clocks affect the way we do our work2. For example, most of us have great difficulty if we must often change to different work hours. _____14____ can take3 many days for a human body to accept the major change in work hours. Dr. Moorhead said industrial officials should have a better understanding of biological clocks and how they affect workers. He said ____15____ understanding could cut sickness and accidents at work and would help increase a factory's production.
- ]& k/ W) f1 e' j7 J) S 1. A scientists B humans C plants D animals- t% O/ v0 i( g) ~3 e, Q D
2. A insects B birds C fish D snakes
9 J4 p- d" ?: V+ G- F7 Q# K# W 3. A effect B affect C effected D affected中 华 考 试 网8 g2 c0 S6 S2 x0 _7 t% e
4. A because B for the reason that C because of D since( F. f G- Q3 A d! Y2 k0 |
5. A months B days C minutes D weeks
- t, D* l2 }# X) z 6. A flight B fly C movement D transportation
( G- |: a r) Y, t6 d5 w 7. A prevented from B ordered by C helped by D intruded on9 l& ?$ d! v/ T1 q
8. A and B but C therefore D however
1 N6 T$ T' J0 Q 9. A portions B parts C sections D kinds
& k4 k+ H4 P/ p( C+ D 10. A try B tries C seem D seems外语学习网7 v+ r M4 y6 W7 E2 w
11. A things B parts C cells D actions0 }; U! d8 q2 x# r, Z$ m' [( q R
12. A awaken B wake C awakening D wake-up8 d8 I. L7 r# e- m
13. A how B why C where D what* C7 L# y: B- w3 z- f, w- v
14. A We B It C They D You
" o+ V" q, X& n7 A 15. A so B with C such D if3 b: ^, A4 B! E7 H K `: z5 _
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