2012职称英语考前每日一练［卫生类A级－11月19日］

　　完形填空题

　　阅读下面的短文，文中有15处空白，每处空白给出了4个选项，请根据短文的内容从4个选项中选择1个最佳答案。

　　A Special Clock

　　Every living thing has what scientists call a biological clock that controls behavior. The biological clock（1）plants when to form flowers and when the flowers should open. It tells insects when to（2）the protective cocoon（防护卵袋）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 because of the（4）of hours of daylight. In the short（5）of winter，its fur becomes white. The fur becomes gray brown in（6）in the longer hours of daylight in summer.

　　Inner signals control other（7）clocks. German scientists found that some kind of internal clock seems to order birds to begin their long migration（8）twice each year. Birds（9）from flying become restless when it is time for the trip，（10）they become calm again when the time of the flight has ended.

　　Scientists say they are beginning to learn which（11）of the brain contain biological clocks. An American researcher，Martin Moorhead，said a small group of cells near the front of the brain（12）to control the timing of some of our actions. These（13）tell a person when to wake，when to（14）and when to seek food. scientists say there probably are other biological clock cells that（15）other body activities.

　　1 A says B asks C tells D talks

　　2 A leave B reach C escape D enter

　　3 A adopt B affect C avoid D express

　　4 A length B value C number D amount

　　5 A months B days C minutes D weeks

　　6 A shape B type C color D form

　　7 A biological B physical C mental D portable

　　8 A flight B operation C movement D transportation

　　9 A prevented B derived C originated D protected

　　10 A unless B but C therefore D if

　　11 A ideas B parts C sorts D images

　　12 A tries B likes C wants D seems