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 open. It tells __2__ when to leave the protective cocoons and fly away，and it tells animals and human beings when to eat, sleep and wake.

　　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.

　　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.

　　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.

　　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,

　　词汇：

　　biological adj.生物(学)的

　　insect n.昆虫

　　cocoon n.防护卵袋，茧

　　fur n.软毛

　　注释：

　　1. 本句中谓语动词tells的宾语由两部分组成。第一部分是when to form flowers，是带疑问副词的动词不定式，第二部分是when the flowers should open,是名词从句。从修辞上说，两者有些不平衡。

　　2. …the way we do our work 可以理解为 the way in which we do our work 或 the way that we do our work.实际上，三种说法都成立。如：

　　He speaks English the way the English people do.

　　I don’t understand the way in which he dealt with the matter.

　　3. take作“花费，花去”解时可用于几种不同的句型：

　　It will take me five days to complete the work.

　　The work will take me five days to complete.

　　To complete this work will take me five days.

　　练习：

　　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. woke 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