单选题
Every living thing has what scientists call a biological clock that controls behavior. It tells plants when to (62) flowers and insects when to leave protective cocoon (茧)and fly away. And it tells animals and human beings when to (63) , sleep and seek food. It controls our body temperatures, the (64) of some hormones and even dreams. Events (65) the plant and animal affect its actions. Scientists recently found that a tiny animal called Siberian hamster changes the color of its (66) because of the number of hours of (67) In shorter days of winter its fur becomes white. The fur becomes gray-brown in longer (68) of daylight in summer. (69) signals control other biological clocks. German scientists found that some internal one seems to order birds to begin their (70) flights two times each year. Birds prevented from flying become (71) when it is time for the trip. (72) they become calm again when the time of the flight has ended. A mix of outside and internal events controls some biological clocks; such things as heartbeat and the daily change from sleep to walking take place because of both external and internal signals. Scientists are beginning to learn (73) parts of the brain contain the biological clocks. A researcher at Harvard University, Dr. Martin Moore Ede, said a small group of cells near the front of the brain seemed to control the (74) of some of our actions. Probably there are other cells to control other body activities. He is studying (75) they affect the way we do our work. Most of us have great difficulty if we (76) often change to different work hours. (77) can take many days for a human body to (78) a major change in work hours. Industrial officials should have a better (79) of biological clocks and how they affect workers. He said such an understanding could (80) sickness and accidents at work, and would help increase (81) .
【正确答案】
A
【答案解析】[精析] 动词辨义[考频：41]。根据语意判断，生物钟可以影响植物开花的时间。而能够和flower构成短语“开花”的词语就是form。 [避错] B)bloom“开花”，bloom一词已包含了flower的意义，后面不接flower；C) blossom “开花的状态”， come into blossom “开花”；D)boom “发出隆隆声，兴隆”，属形近易混词。
【答案解析】[精析] 语意判断[考频：5]。在上下文中我们得知，the fur becomes gray-brown in longer (68) of daylight in summer.(皮毛在夏天长时间日光照射下会变成棕灰色。)可以判断应该是日光照射的小时数影响了该动物皮毛颜色的变化。daylight表示“日光”，所以B)正确。
【答案解析】[精析] 语意题[考频：5]。该句后面的一句话为我们提供了解题的线索；German scientists found that some internal one seems to...，因此我们判断身体内部的信号也能控制生物钟。Inner意为“内部的”，故选择C)。 [避错] A)inward “向内的”，指朝着中心或内部方向的，侧重方向而不是位置；B)outer “外部的”；D)other“其他的”。
【正确答案】
A
【答案解析】[精析] 名词辨义[考频：37]。通过下文when it is time for the trip 得知，鸟类开始的这次飞行应该是“迁徙”。 migration“移民，移动”，泛指从一个地方到另一个地方定居，不一定是国家和国家之间，因此选择A)。 [避错] B)immigration“外来的移民移居入境”，是移居到说话人所在的国家，并且获得公民身份和获得永久权；C)emigration“移民出境”，是指离开说话人所在的国家移居到别处去，D)transportation“交通运输”。
【正确答案】
C
【答案解析】[精析] 形容词辨义[考频：16]。通过下文我们得知，they become calm again when the time of the flight has ended当鸟类迁徙结束后，它们又恢复了平静。因此可以判断，当迁徙时间已到，而又被阻止不能迁徙的鸟类应有的状态是“不平静的”(calm的反义词)。restless表示“不平静的，不安宁的”，所以选择C)。 [避错] A)ruthless“无情的，残忍的”；B)annoyed“苦恼的”；D)anxious“担忧的，渴望的”。
【答案解析】[精析] 考查疑问词[考频：3]。通过下文a small group of cells near the front of the brain seemed to control the (73) of some of our actions可知，研究者们研究的是大脑哪些部位起作用，因此选择B)。
【正确答案】
D
【答案解析】[精析] 语意题[考频：5]。在文章第一段作者就已经告诉我们生物钟的作用：It tells plants when to form... the release of some hormones and even dreams.可知大脑中一些细胞是能控制某些行为的时间选择的(即上文的when to do sth. )。timing表示“时间选择，调速”，所以选择D)。 [避错] A)motion “运动，动作”；B)rhythm “节奏，韵律”；C)step “步骤，脚步”。