A Biological Clock3 P d9 V+ M! m6 Q2 |/ t" t
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 open. 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.
4 w2 P; v/ Z( N; T) z8 w: `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 in summer.
5 @ N# J9 Q# E @; @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__ from flying become restless when it is time for the trip, __8__ they become calm again when the time of the flight has ended.
0 {3 y5 R* R* O2 I( IScientists 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." H, |) K5 a4 M' n7 Q: B
Dr. Moorhead is studying __13__ our biological clocks affect the way we do our work. For example, most of us have great difficulty if we must often change to different work hours. __14__ can take 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.6 J. h8 m$ r7 a9 C0 P2 z
1. A) scientists B) humans C) plants D) animals
% u1 a' m- {1 v) Y! x2 p5 @% l2. A) insects B) birds C) fish D) snakes! G% `" c5 f: s3 i
3. A) effect B) affect C) effected D) affected3 k, e" Q6 x1 A
4. A) because B) for the reason that C) because of D) since* g' `" v' P' U' s5 |! y1 v1 U$ B
5. A) months B) days C) minutes D) weeks8 t/ p2 i4 e0 f7 Z1 w3 _( c7 b. F
6. A) flight B) fly C) movement D) transportation
+ F# {. Y0 _4 u+ D6 e5 H7. A) prevented from B) ordered by C) helped by D) intruded on
. D4 r* e' ?6 I& N8. A) and B) but C) therefore D) however6 `; N: R! m3 R& Z7 x' Z
9. A) portions B) parts C) sections D kinds- Z i9 m% d2 u( i- s
10. A) try B) tries C) seem D) seems
2 p# z% U( O5 t: x w; d+ D' r+ |3 h11. A) things B) parts C) cells D) actions
' a% j' j% ?3 O) }. n I& e- F12. A) awaken B) wake C) awake D) wake-up. w3 E: W6 U o3 b4 z+ l# }. e
13. A) how B) why C) where D) what2 \) _4 r6 r" P! q0 e+ I$ A+ S
14. A) We B) It C) They D) You, g- n8 h( z9 x
15. A) so B) with C) such D) if
- l7 K% m- J9 l' A1 o6 }KEYS: CABCB AABBD CAABC |