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
KEYS: CABCB AABBD CAABC
六级英语作文怎样最好的利用课本
六级英语我对承诺的看法
六级英语作文健康和财富
六级英语向盗版说不
六级作文了解校园外面的世界
六级作文人口增长与计划生育
六级英语作文电视破坏了友谊和家庭
六级英语作文增加词汇量的好处
名师指导2013年英语四六级作文考前高分技巧
六级作文网上求职
2013年12月英语六级作文预测选择职业
六级英语作文如何应考
六级英语作文现代科技使生活更加便捷
六级作文东京—重建之城
六级作文谁应该对我们的老人们负责任
六级英语语言学习成功者的奥秘
六级英语:看电影是不是比阅读小说更愉快
2013年12月英语六级作文预测减少校园浪费
六级作文色彩的奇迹
六级英语作文能的来源
六级英语学生需要心理健康
六级英语作文人生感言
2013年12月英语六级作文预测城市交通问题
六级英语作文金钱与荣誉
六级英语作文当老师的第一天
六级作文我对西方文化的欣赏
六级作文从我做起杜绝浪费
考研英语作文肤浅的“爱国主义”
六级英语时间给了家庭朋友和社会
六级作文老师讲课要有趣好玩
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |