阅读下面的短文。短文中有15个空白，在文章的后面，每空白都列出了四个备选答案。

　　请文章的内容选择合适的词或短语填在空白处。

　　A Biological Clock

　　Every living thing has what scientists call a biological clock that controls

　　behavior. The biological clock tells _________when to form flowers and when the

　　flowers should open1. It tells _________ 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 anima __________the actions of some biological

　　clocks. Scientists recently found, for example, that a tiny animal changes the

　　color of its fur________ the number of hours of daylight . In the short _________

　　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

　　__________ twice each year. Birds __________ flying become restless when it is

　　time for the trip, ___________ they become calm again when the time of the flight

　　has ended.

　　Scientists say they are beginning to learn which ____________ of the brain

　　contain biological clocks. An American researcher, Martin Moorhead, said a small

　　group of cells near the front of the brain __________to control the timing of

　　some of our actions. These _________ tell a person when to ___________ , 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 _________ 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. __________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 ________ understanding could cut sickness and accidents at work and would

　　help increase a factory’s production.

　　词汇：

　　biological adj. 生物(学)的 migration n.迁徙

　　insect n.昆虫 restless adj.焦躁不安的

　　cocoon n.防护卵袋，茧 contain v.含有

　　fur n.软毛 cell n. 细胞

　　注释：

　　1、 句中谓语动词tells 的宾语有两组成。 是when to form flowers, 是带

　　疑问浮词的动词不定式，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. 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)wake C)awakenin