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
英语六级考试词汇的秘诀
名师解析英语六级考试大纲单词的核心难词(H)
大学英语六级语法中关于虚拟语气要点
整理六级高频词汇
英语六级完形填空务必掌握重要表达
大学英语六级考试倒计时必备
词根记词法帮你迅速记忆六级单词
英语六级考试大纲核心难词汇总
英语六级常考难记单词冲刺记忆圣经
冲刺必看英语六级考试1300个核心词汇总结
英语六级考试名师指导语法篇
大学英语六级词汇的考试的特点
六级各组核心的词汇
大学英语六级考试语法的复习
英语六级考试核心分类词汇的总结
英语六级考试一定要记住的四个单词
大学英语六级考试高频词汇用法的总结
总结归纳的英语六级必考500词
大学英语六级词汇部分历年出题特点的总结
英语六级考试词汇巧学习(第一期)
英语六级单选正确选项高频词汇的总结
英语六级考试阅读理解中表示考官主旨的词汇
英语六级完形填空预测
英语六级考试常考名词分类总结
英语六级考试词汇记忆看对话记单词20
六级黑宝典系列市长给示威者送水和食品
大学英语六级考试必背词汇500个
英语六级考试翻译预测
新英语六级考试常用的词汇搭配116条
大学英语六级考试高分经验谈完型填空
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |