第二篇 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 cocoons 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__ 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 factory’s production,
词汇：
biological adj.生物(学)的
insect n.昆虫
cocoon n.防护卵袋，茧
fur n.软毛
注释：
1. 本句中谓语动词tells的宾语由两部分组成。第一部分是when to form flowers，是带疑问副词的动词不定式，第二部分是when the flowers should open,是名词从句。从修辞上说，两者有些不平衡。
2. …the way we do our work 可以理解为 the way in which we do our work 或 the way that we do our work.实际上，三种说法都成立。如：
He speaks English the way the English people do.
I don’t understand the way in which he dealt with the matter.
3. take作“花费，花去”解时可用于几种不同的句型：
It will take me five days to complete the work.
The work will take me five days to complete.
To complete this work will take me five days.
练习：
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. woke C. awakening 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
答案与题解：
1. C 从后半句 When to form flowers and when the flowers should open 知道，只有 plants 才有花。前面没有定冠词修饰的plants是泛指植物这一大类，与动物类相对应。
2. A 后面出现的 when to leave the protective cocoons and fly away 提示我们，唯有选 insects 才是正确的，因为只有insects才有protective cocoons,而birds、fish和snakes都没有。
3. B affect作为动词是“影响”的意思，而effect作为动词则是“使发生;使生效”的意思。这里谈论的是动植物生物钟的一般情况，所以使用动词的一般现在时。
4. C这里应使用介词短语，因为其后是名词。because和since都有“因为”的意思，但它们都是连词，用来引导原因状语从句,如:
He will not come because he is ill.
Since he is ill, he will not come.
for the reason that后接句子，所以也不是答案。
5. B 根据下句中的 in the longer hours of daylight in summer 和上句中的 the number of hours of daylight,以及该段的中心意思，可以判断，应选择B,因为冬天日短夜长,夏天则反之。
6. A本句中有birds，migration这些词，下一句又谈及迁徙飞行前的躁动不安，就知道应该填词义为“飞行”的名词。fly是动词，不能选择;其他两个选项也都不合适。flight是fly的名词形式，所以是合适的选择。
7. A该句句子的主干是：主语birds,谓语become restless。所以，所填的词是过去分词，修饰 birds。从上下文表达的意思判断,ordered by (被命令)、helped by (被帮助)和intruded on(被强加)都不匹配，只有prevented from是合适的选择。
8. B很明显，这里需使用连词，连接该句中平行的两个分句。而根据整个句子的句意，上半句和下半句形成反差对比：become restless when the time of the flight has ended，所以应选择but,表示相反的两层意思。
9. B portion是“一定数量;一份”, section是“切下的部分”，kind是“种类”，都不符合上下文意思连贯的要求。唯有B是正确的选项。
10. D不能选择C,因为主语是group,而不是cells，所以要采用动词的第三人称单数形式 seems A和B不符合常识。
11. C These 一词说明，其后的名词是上文已经提到的某些事物，即cells。从下文中可以看出，尽管actions —词也在上文中出现,但该词不符合句意。选项A和B意思不准确。
12. A该句中的三个宾语都是带疑问副词的动词不定式，所以都要用动词原形。awaken是唯一合适的选择，woke是wake的一般过去形式,awakening是形容词,wake-up是名词。
13. A studying后面是一个从句作它的宾语,而从句起首处应有个连词。把C或D填入空格 上下文意思不连贯。根据下文的例子，作者讨论的不是生物钟为什么会影响我们的工作， -而是生物钟如何影响我们的工作。所以，how是正确的选择。 14. B从句子结构中不难看出，to accept the major change in work hours是实际上的主语，而此 处需要一个形式主语，所以只能选择It。
15. C该句中的understanding既然是上句中提到的better understanding, C便是最佳的选项。其他三个选项均不符合语法。
参考译文
第二篇 生物钟
每一种生物都有控制它们行为的时钟，科学家们称之为生物钟。生物钟告诉植物的花朵何时生长，何时开放;生物钟告诉昆虫何时离开防护卵袋，远远飞去;生物钟还告诉动物和人类何时进食、睡眠，何时苏醒。
外界的变化会影响某些动植物的生物钟。例如，科学家最近发现，有一种很小的动物，会随着白天日照时间的长短改变其毛发的颜色。冬季日照时间短，它的毛变成白色。夏季白天日照时间长，它的毛又变成棕灰色。
还有的生物，它们的生物钟受体内信号控制。德国的科学家发现，鸟类体内的某种生物钟迫 使它们每年做两次长距离迁移。那些被迫不能迁移的鸟，当迁移时间到来时，会显得烦躁不安，而当这段时间过后，它们又恢复了平静。
科学家们指出，他们开始探索大脑内部的哪些部位存在生物钟。一位美国的研究员，马丁• 莫亥德(Martin Moorhead)曾指出，好像是人脑前部的一小群细胞控制着人体的行为。这些细胞控制着人体睡眠、苏醒和觅食的时间。另外，科学工作者推测，可能还有另外的生物钟细胞控制人体的其他行为。
目前，莫亥德博士正在研究生物钟对人们工作方面的影响。比如，如果经常改变工作时间， 绝大多数人会感觉不适应。要适应工作时间上的较大变动，可能需要相当长一段日子。莫亥德博士说，工厂的领导应该对生物钟有进一步的了解，懂得生物钟对工人的影响，如此则会减少工作 中的不适和事故，对提高生产大有裨益。
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