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
考研
All animals must rest, but do they really sleep as we know it? The answer to this question seems obvious. If an animal regularly
All animals must rest, but do they really sleep as we know it? The answer to this question seems obvious. If an animal regularly
admin
2014-06-13
32
问题
All animals must rest, but do they really sleep as we know it? The answer to this question seems obvious. If an animal regularly stops its activities and stays quiet and unmoving—if it looks as though it is sleeping—then why not simply assume that it is in fact sleeping? But how can observers be sure that an animal is sleeping?
They can watch the animal and notice whether its eyes are open or closed, whether it is active or lying quietly, and whether it responds to light or sound. These factors are important clues, but they often are not enough. Horses and cows, for example, rarely close their eyes, and fish and snakes cannot close them. Yet this does not necessarily mean that they do not sleep. Have you ever seen a cat dozing with an eye partly open? Even humans have occasionally been observed to sleep with one or both eyes partially open. Animals do not necessarily lie down to sleep either. Elephants, for example, often sleep standing up, with their tusks resting in the fork of a tree. Finally, while "sleeping" animals often seem unaware of changes in the sounds and light and other stimuli around them, that does not really prove they are sleeping either.
Observations of animal behavior alone cannot fully answer the question of whether or not animals sleep. The answers come from doing experiments in "sleep laboratories" using a machine called the electroencephalograph (EEC). The machine is connected to animals and measures their brain signals, breathing, heartbeat, and muscle activity. The measurements are different when the animals appear to be sleeping than when they appear to be awake. Using the EEC, scientists have confirmed that all birds and mammals studied in laboratories do sleep. There is some evidence that reptiles, such as snakes and turtles, do not truly sleep, although they do have periods of rest each day, in which they are quiet and unmoving. They also have discovered that some animals, like chimpanzees, cats, and moles (who live underground), are good sleepers while others, like sheep, goats, and donkeys, are poor sleepers. Interestingly, the good sleepers are nearly all hunters with resting places that are safe from their enemies. Nearly all the poor sleepers are animals hunted by other animals: they must always be watching for enemies, even when they are resting.
The statement, "Horses and cows, for example, rarely close their eyes" aims to show that______.
选项
A、these animals rarely need any rest
B、they almost always keep alert to danger
C、they often stay awake
D、their eyes are rarely closed even when they are asleep
答案
D
解析
作者在第二段说,马和牛很少闭上眼睛,但这并不能说明它们不睡觉,事实上它们睡觉的时候眼睛经常是睁开的。
转载请注明原文地址:https://kaotiyun.com/show/AaO4777K
0
考研英语一
相关试题推荐
"Thisisareallyexcitingtime—aneweraisstarting,"saysPeterBazalgette,thechiefcreativeofficerofEndemol,thetelev
Inthefollowingtext,somesentenceshavebeenremoved.ForQuestions41-45,choosethemostsuitableonefromthelist(A、B、C、
Accordingtotheauthor,theAmericaneconomicsituationis______.The1978-1987averagesofproductivityarelessthan______
Cats,accordingtotheauthor,______.Thepassageconcludesthat______.
Thereasonwhypeoplemightnotbeabletostayaliveinaworldwithoutemotionisthat______.Accordingtothepassage,peopl
Howdoestheauthorthinkofhimself?Itcanbeinferredfromthepassagethattheauthorwantsto
Itcouldbeinferredthatthewriterthinksthat,incomparisonwiththemovementofmillionsofhungryandjoblesspeoplefrom
Nowa.dayspeoplearelikelytofeelthatthey______.Onehundredyearsago,peoplewere______.
ThatLouiseNevelsonisbelievedbymanycriticstobethegreatesttwentieth-centurysculptorisallthemoreremarkablebecaus
Lowlevelsofliteracyandnumeracyhaveadamagingimpactonalmosteveryaspectofadults,accordingtoasurveypublishedyes
随机试题
我国的沼泽可分为( )、( )、( )。
一般送检分离培养含病毒标本的最佳温度为
患者于某,男性,56岁。患肺痨5年,症见咳嗽无力,声低懒言,痰中带血,血色淡红,午后低热,面白颧红,舌嫩红有齿痕,苔薄白,脉细弱数。其治疗应首选的方剂是
环境中常见的二次污染物有
2008年4月,中国东方公司与美国神奇公司签订了一份货物买卖合同,双方在买卖合同中约定如果合同履行发生争议,则双方应将争议提交伦敦的仲裁机构解决。东方公司收到货物以后,发现神奇公司提供的货物不符合合同的约定,遂于2008年10月10日向中国某人民法院提起诉
公司增发的普通股的市价为12元/股,筹资费用率为市价的6%,本年发放股利每股0.6元,已知同类股票的预计收益率为11%,则维持此股价需要的股利年增长率为( )。
(接上题)钟老师与他人合资成立的税务师事务所于2010年顺利开张,进入2011年发展很是迅速,场所、车辆皆不敷使用,相继采取下列措施:①事务所委托某外贸公司进口九成新凌志小轿车一辆,海关核定关税完税价格为20万元人民币,该车已交付事务所使用。②钟老师将
从所给的四个选项中,选择最合适的一个填入问号处,使之呈现一定的规律性。
Manypeoplewhoflyatleastoccasionallyhavecomedownwithacoldortheflushortlyafterdisembarking.Istheairinairbor
Thegovernmentisthinkingof______heavytaxesoncigarettestoraiseextrarevenue.
最新回复
(
0
)