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
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
2017-03-25
56
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 un-moving—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
本题可参照第二段,即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。据此可知D项为正确答案。
转载请注明原文地址:https://kaotiyun.com/show/ifGO777K
0
考博英语
相关试题推荐
Openupmostfashionmagazinesandyouwillseeincrediblythinmodelswithimpossiblehairandwearingunreasonablyexpensive,
Tomanagerhopingtoblossomasabusinessleadermustdeveloptheskilltocommunicateeffectively.Oneoftheforemosttaskso
Ifwewereaskedexactlywhatweweredoingayearago,weshouldprobablyhavetosaythatwecouldnotremember.Butifwehad
Heclaimsthatadvertisingtodaytendstoportraywomenintraditionalrolessuchascookingortakingcareofthebaby.
Ifweacceptthatwecannotpreventscienceandtechnologyfromchangingourworld,wecanatleasttryto【C1】______thatthecha
Throughouthistorynewtechnologieshaverevolutionizedwarfare,sometimesabruptly,sometimesonlygradually:thinkofgunpowde
Withoutexposuretothecultural,intellectual,andmoraltraditionsthatareourheritage,weareexcludedfromacommonworld
Thestudyofgeneticshasgivenrisetoaprofitablenewindustrycalledbiotechnology.Asthename【C1】______,itcombinesbiolo
Underthe______thatweneededmoneybadly,wehadtoacceptaverylowpricewhenwesoldthehouse.
Thistypeofchair,easily______orfoldedaway,isidealforuseinthegarden.
随机试题
在一个程序中,同一地址号的线圈()次输出,且继电器线圈不能串联只能并联。
打开目的层后,起下管柱前,要试关环形防喷器一次以()。
已婚女性,停经56天,恶心、呕吐、不能进食8天就诊,其辅助检查结果不正确的是
对血液库存时间无要求的病种输血时,配发血的原则是
治疗血淋、尿血属实热证的常用方剂为
田某,女,50岁,右上腹部疼痛1天。体温39℃,巩膜黄染,B型超声示胆总管结石,为警惕急性重症胆管炎,病情观察中要特别注意( )。【历年考试真题】
不属于防火或安全使用的玻璃是()。
下面是某求助者的MMPI一2的测验结果:(2011年5月真题)对于MMPI-2的解析,正确的包括()。
Scienceisstill______ofthecausesofmanykindsofcancer.
下列查找方法中平均查找长度与元素的个数无关的方法是()。
最新回复
(
0
)