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
2013-01-12
80
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.
Animals that are good sleepers ______.
选项
A、need to have a good sleep after they have exhausted themselves by getting rid of hunting animals
B、need to have a good sleep after they get tired from hunting other animals
C、are all mammals
D、almost always have a safe resting place
答案
D
解析
转载请注明原文地址:https://kaotiyun.com/show/1a9O777K
0
考博英语
相关试题推荐
Iamafraidthatyouhavetoalteryour______viewsinlightofthetragicnewsthathasjustarrived.
Althoughwomenclustertohimlikemothsaroundaflame,heisnone______happierforit.
Sheisfurious(of)herson’sgradesinschool,(which)explainswhyMarkisjealous(of)Julia’shighmarks(on)theexam.
Severalguestswerewailingonthe______forthefrontdoortoopen.
Weneedonehundredmoresignaturesbeforewetakethe______tothegovernor.
Thisteachingmethodisa______ofmanymethodswhichhavebeenusedfordecadesinthecountry.
Asanindustry,biotechnologystandsto______electronicsindollarvolumegridperhapssurpassitinsocialimpactby2020.
Thesinglegreatestshiftinthehistoryofmass-communicationtechnologyoccurredinthe15thcentury,andwaswelldescribedb
Theex-presidenthadbeen______inthecountrytorefreshhismindbeforehepassedaway.
Idon’tmindabitifyoubringyourfriendsinforadrink,butitisrathertoomuchwhentenpeoplearrive____fordinner.
随机试题
目前,对外汇的限制主要在()
下列疾病中,可产生杵状指的是【】
患者,女,37岁,停经59天,妊娠反应10余日,今日突然阴道出血就诊,妇科检查发现子宫孕3个月大小,子宫两侧扩及4cm×3cm×5cm的囊性包块,宫颈口有少量血液流出。考虑可能为
不属于颗粒剂质量检查项目的是
土的CBR值指试料贯入量达2.5mm时,单位压力对哪种压入相同贯入量时荷载强度的比值?()
下列财务指标中,可以用来反映公司资本结构的有()。
公开发行公司债券,股份有限公司的净资产应当不低于人民币()。
在窗体上画一个名称为Command1的命令按钮,然后编写如下通用过程和命令按钮的事件过程;PrivateFunctionfun(ByValmAsInteger)IfmMod2=0Thenf
以下叙述错误的是()。
给英语老师发一封电子邮件,并将考生文件夹下的文本文件homework.txt作为附件一起发送。具体要求如下:【收件人】wanglijuan@cuc.edu.cn【主题】课后作业【内容】王老师,您好!我的作业已经完成,请批阅。具体见附件。
最新回复
(
0
)