A Biological Clock
Every living thing has what scientists call a biological clock that controls behavior. The biological clock tells ___C__1___ when to form flowers and when the flowers should open1. It tells ___A__2____ when to leave the protective cocoon and fly away, and it tells animals and human beings when to eat, sleep and wake.
Events outside the plant and animal ___B__3_____ the actions of some biological clocks. Scientists recently found, for example, that a tiny animal changes the color of its fur __C__4_____ the number of hours of daylight. In the short ____5__B_ of winter, its fur becomes white. The fur becomes gray brown in color in the longer hours of daylight summer.
Inner signals control other biological clocks. German scientists found that some kind of internal clock seems to order birds to begin their long migration ___A__6____ twice each year. Birds ____A_7_____ flying become restless when it is time for the trip, _B___8___ they become calm again when the time of the flight has ended.
Scientists say they are beginning to learn which __B__9____ of the brain contain biological clocks. An American researcher, Martin Moorhead, said a small group of cells near the front of the brain __D__10____ to control the timing of some of our actions. These ___C_11____ tell a person when to ___A__12_____, when to sleep and when to seek food. Scientists say there probably are other biological clock cells that control other body activities.
Dr. Moorhead is studying __A___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. ___B__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 __C__15____ understanding could cut sickness and accidents at work and would help increase a factorys production.
1. A) scientists B) humans C) plants D) animals
2. A) insects B) birds C) fish D) snakes
3. A) effect B) affect C) effected D) affected
4. A) because B) for the reason that C) because of D) since
5. A) months B) days C) minutes D) weeks
6. A) flight B) fly C) movement D) transportation
7. A) prevented from B) ordered by C) helped by D) intruded on
8. A) and B) but C) therefore D) however
9. A) portions B) parts C) sections D) kinds
10. A) try B) tries C) seem D) seems
11. A) things B) parts C) cells D) actions
12. A) awaken B) wake C) awakening D) wake-up
13. A) how B) why C) where D) what
14. A) We B) It C) They D) You
15. A) so B) with C) such D) if
精选英语美文阅读:A Friend's Prayer 朋友的祈祷
英语美文:生命这个奇迹
浪漫英文情书精选:Is It Love?这是爱么?
精选英语美文阅读:爱的奇迹 Keep on Singing
浪漫英文情书精选:Need You With Me需要你爱我
美文欣赏:海边漫步
英语美文30篇系列之21
精美散文:守护自己的天使
精选英语散文欣赏:一棵小苹果树
双语美文欣赏:孤独人生
英语美文:Keep on Singing
浪漫英文情书精选:Don't Give Up不要放弃
精选英语美文阅读:哪有一株忘忧草? (双语)
26个英文字母蕴含的人生哲理
精选英语美文阅读:假如生活欺骗了你
浪漫英文情书精选:My Heart And Soul我的灵魂
英文《小王子》温情语录
精选英语美文阅读:无雨的梅雨天 (双语)
精选英语美文阅读:一封未发出的英文情书《但是你没有》
精选英语散文欣赏:微笑挽救生命
人生哲理:年轻无悔 别停下追寻梦想的脚步
生命可以是一座玫瑰花园
伤感美文:人生若只如初见
精选英语美文阅读:被忽略的爱 Helpless love
精选英语美文阅读:山居秋暝
精选英语美文阅读:饶孟侃《呼唤》
精美散文:让我们撩起生命的波纹
精选英语散文欣赏:平等的爱
态度决定一切 Attitude Is Everything
英语美文:越长大越孤独(双语)
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |