首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Every living thing has what scientists call a biological clock that controls behavior. It tells plants when to【C1】______ flowers
Every living thing has what scientists call a biological clock that controls behavior. It tells plants when to【C1】______ flowers
admin
2010-10-28
35
问题
Every living thing has what scientists call a biological clock that controls behavior. It tells plants when to【C1】______ flowers and insects when to leave protective cocoon (茧)and fly away. And it tells animals and human beings when to【C2】______ , sleep and seek food. It controls our body temperatures, the【C3】______ of some hormones and even dreams.
Events 【C4】______ the plant and animal affect its actions. Scientists recently found that a tiny animal called Siberian hamster changes the color of its【C5】______ because of the number of hours of【C6】______ In shorter days of winter its fur becomes white. The fur becomes gray-brown in longer【C7】______ of daylight in summer.
【C8】______ signals control other biological clocks. German scientists found that some internal one seems to order birds to begin their【C9】______ flights two times each year. Birds prevented from flying become【C10】______ when it is time for the trip.【C11】______ 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【C12】______ 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【C13】______ of some of our actions. Probably there are other cells to control other body activities. He is studying【C14】______ they affect the way we do our work. Most of us have great difficulty if we【C15】______ often change to different work hours.【C16】______ can take many days for a human body to【C17】______ a major change in work hours. Industrial officials should have a better【C18】______ of biological clocks and how they affect workers. He said such an understanding could【C19】______ sickness and accidents at work, and would help increase【C20】______ .
【C15】
选项
A、may
B、can
C、must
D、might
答案
C
解析
考查情态动词 。情态动词的使用应该参照语境。人们更换工作时间一般是迫不得已而为之,因此只有等到必须做的时候才会更换。must表示“必须”,所以C项正确。
转载请注明原文地址:https://jikaoti.com/ti/bVeFFFFM
0
大学英语六级
相关试题推荐
Althoughthefactthattodayvirusesareknownto【S1】______causecancerinanimalsandincertainplants,tha
Althoughthefactthattodayvirusesareknownto【S1】______causecancerinanimalsandincertainplants,tha
Althoughthefactthattodayvirusesareknownto【S1】______causecancerinanimalsandincertainplants,tha
Althoughthefactthattodayvirusesareknownto【S1】______causecancerinanimalsandincertainplants,tha
Althoughthefactthattodayvirusesareknownto【S1】______causecancerinanimalsandincertainplants,tha
Livingisrisky.Crossingtheroad,drivingacar,flying,swallowinganaspirintabletoreatingachickensandwich--theycana
Livingisrisky.Crossingtheroad,drivingacar,flying,swallowinganaspirintabletoreatingachickensandwich--theycana
A、Movehisplantsawayfromthewindow.B、Watertheplantsmoreoften.C、Lettheplantshavemoresunlight.D、Lethertakecare
A、Sheknowsalargerapartmenthecanrent.B、Sheisusedtolivinginalargeapartment.C、Sheknowstheman’sneighborismovi
Weallscreamforwaterwhenthirsty,butdoyouknowinveryhot,dryweather,plantsalsomake【B1】______soundsasiftheya
随机试题
下列哪种因素不是引起新生儿坏死性小肠炎的因素
代谢性碱中毒时实验室检查可出现
下列关于围绝经期综合征妇女的护理,不正确的是
药典中浓氨溶液中NH3的浓度表示法为
A.心肌能量生成障碍B.心室顺应性↓C.心肌收缩蛋白破坏D.心肌兴奋-收缩耦联障碍E.心肌能量贮存障碍贫血引起心肌收缩性↓主要因为
甲公司是汽车制造业一般纳税人,2016年8月,因经营需要拟新增办公楼一栋,对新增办公楼涉税政策,向税务师咨询如下问题:若购买的办公楼按10年计提折旧,无残值,2016年8月投入使用,先用于职工食堂,2017年9月,甲欲将其改为办公楼,按现行规定,201
下列关于准时生产系统(JIT)的表述中,正确的是()。
将考生文件夹下LAY\ZHE文件夹中的XIAO.DOC文件复制到同一文件夹下,并命名为JIN.DOC。
LakeSuperior,(partof)theUnitedStates-Canadian(boundary),is(a)largestfreshwaterlakeinthe(world).
Whichofthefollowingisakeycomponentofthecourse?
最新回复
(
0
)