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 cocoon 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__ from 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 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) awake 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
答案: CABCB AABBD CAABC
2017届高考英语一轮复习话题语汇狂背课件:话题21(新人教版)
2017年高考英语精品课堂基础版之预习学案:专题04《making the news》(新人教版必修5原卷版)
2017年高考英语精品课堂基础版之预习学案:专题01《great scientist》(新人教版必修5原卷版)
2017届高考英语一轮复习写作指导课件:子润色 简单句的高级形式(新人教版)
2017届高考英语一轮复习写作指导课件:句子主要成分(新人教版)
2017届高考英语一轮复习语法讲解课件:介词(新人教版)
2017届高考英语一轮复习写作指导课件:篇章润色 如何做到篇章结构连贯(新人教版)
2017年高考英语精品课堂基础版之预习学案:专题04《making the news》(新人教版必修5教师版)
2017届高考英语一轮复习语法讲解课件:名词(新人教版)
2017年高考英语精品课堂基础版之课时训练:专题02《the united kingdom》(新人教版必修5教师版)
2017届高考英语一轮复习话题语汇狂背课件:话题18(新人教版)
2017年高考英语精品课堂基础版之课时训练:专题03《life in the future》(新人教版必修5原卷版)
2017年高考英语精品课堂基础版之自主检测:专题01《great scientist》(新人教版必修5教师版)
2017年高考英语精品课堂基础版之课时训练:专题04《making the news》(新人教版必修5教师版)
2017届高考英语一轮复习语法讲解课件:构词法(新人教版)
2017年高考英语精品课堂基础版之预习学案:专题03《life in the future》(新人教版必修5教师版)
2017年高考英语精品课堂基础版之课时训练:专题03《life in the future》(新人教版必修5教师版)
2017年高考英语精品课堂基础版之重点讲解:专题01《great scientist》(新人教版必修5原卷版)
2017年高考英语精品课堂基础版之课时训练:专题02《the united kingdom》(新人教版必修5原卷版)
2017届高考英语一轮复习语法讲解课件:非谓语动词(新人教版)
2017届高考英语一轮复习写作指导课件:句子润色 用高级结构让句子靓起来(新人教版)
2017年高考英语精品课堂基础版之重点讲解:专题03《life in the future》(新人教版必修5原卷版)
2017届高考英语一轮复习写作指导课件:篇章润色 记叙文的语篇连接词(新人教版)
2017届高考英语一轮复习话题语汇狂背课件:话题17(新人教版)
2017年高考英语精品课堂基础版之重点讲解:专题05《first aid》(新人教版必修5教师版)
2017届高考英语一轮复习语法讲解课件:并列连词(新人教版)
2017年高考英语精品课堂基础版之预习学案:专题05《first aid》(新人教版必修5原卷版)
2017届高考英语一轮复习话题语汇狂背课件:话题15(新人教版)
2017年高考英语精品课堂基础版之预习学案:专题02《the united kingdom》(新人教版必修5教师版)
2017届高考英语一轮复习语法讲解课件:情态动词(新人教版)