职称英语综合类考试必备练习题之完形填空(3)

　　A Special Clock

　　Every living thing has what scientists call a biological clock that controls behavior. The biological clock________ plants when to form flowers and when the flowers should open. It tells insects when to __________ 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__________ the actions of some biological clocks . Scientists recently found, for example, that a tiny animal changes the color of its fur because of the __________ of hours of daylight. In the short_________ of winter, its fur becomes white. The fur becomes gray brown in _________ in the longer hours of daylight in summer.

　　Inner signals control other _________ clocks. German scientists found that some kind of internal clock seems to order birds to begin their long migration_________ twice each year. Birds _________ from 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 wake, when to _________ and when to seek food. Scientists say there probably are other biological clock cells that __________ other body activities.

　　51 A says B asks C talks D tells

　　52 A reach B leave C escape D enter

　　53 A affect B adopt C avoid D express

　　54 A time B value C amount D number

　　55 A days B months C minutes D weeks

　　56 A shape B type C form D color

　　57 A physical B biological C mental D portable

　　58 A operation B flight C movement D transportation

　　59 A derived B prevented C originated D protected

　　60 A but B unless C therefore D if

　　61 A parts B ideas C sorts D images

　　62 A tries B likes C seems D wants

　　63 A functions B places C actions D cells

　　64 A lie B sleep C stand D walk

　　65 A build B demand C reflect D control

　　答案：51.D 52.B 53.A 54.D 55.A 56.D 57.B 58.B 59.B 60.A 61.A 62.C 63.D 64.B 65.D