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
54
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.
According to the author, all animals ______.
选项
A、spend some time resting
B、close their eyes when sleeping
C、are good sleepers
D、are poor sleepers
答案
A
解析
转载请注明原文地址:https://kaotiyun.com/show/La9O777K
0
考博英语
相关试题推荐
PerhapsIshouldnothavedoneso,butIchangedmymindaboutthenewjobeventhoughIwas______lastweek.
Idon’tthinkthatthisquestionissubordinate______themainaimofourcompany.
Thelocalgovernmentleadersaremakingeveryeffortto______theproblemofpoverty.
Motorwaysare,nodoubtthesafestroadsinBritain.Mile【21】mile,vehicleforvehicle,youaremuch【22】likelytobekilledors
Thefoodyoueatdoesmorethanprovideenergy.Itcanhaveadramaticeffectonyourbody’sabilitytofightoffheartdisease,
Althoughhehashadnoformaleducation,heisoneofthe______businessmeninthecompany.
Theex-presidenthadbeen______inthecountrytorefreshhismindbeforehepassedaway.
Ishouldbeabletofinishthetaskontime,______youprovidemewiththenecessaryguidance.
Dinnerwillbeready______,butwestillhavetimeforadrink.
HowtoGetPreservedasaFossil(66)Unfortunatelythechangesofanyanimalbecomeafossilarenotverygreat,and(67)t
随机试题
成熟中性粒细胞过氧化物酶活性减低的疾病是
患者,男,30岁。因龋坏拔除,给予2%利多卡因行下牙槽神经阻滞麻醉,未行注射器回抽,注射后患者出现烦躁不安、多话、颤抖、恶心、气急、全身湿冷、脉速、血压升高。可能的原因是
A、推动作用B、温煦作用C、防御作用D、固摄作用E、气化作用多尿是与气的哪项功能失常有关
[2006年第049题]以下哪项不符合方案设计文件的编制深度要求?
持有会计从业资格证书的人员,离开会计工作岗位超过()个月的,应当填写注册登记表,并持会计从业资格证书,向原注册登记的会计从业资格管理机构备案。
唐老师准备参加全市幼儿园教师基本技能大赛,因缺乏参赛经验,就去请教经常担任各类大赛评委的谢老师,但总被谢老师拒绝。谢老师的做法()。(2017年上半年真题)
人生不可能是尽善尽美的,我们也很难找到一朵花是完美无缺的。虽然人体总的来说是左右对称的,可是这种对称远远不是完全的。每个人左右手的粗细不一样,一只眼睛比另一只眼睛更大或更圆。两个耳垂的形状也不同。最明显的,就是每个人只有一个心脏,通常都在靠左的位置。
第二语言教学中通常所谓的“听说读写”指的是四种______。
关于因特网中的主机和路由器,以下________说法是正确的。Ⅰ.主机通常需要实现TCP协议Ⅱ.路由器必须实现TCP协议Ⅲ.主机必须实现p协议Ⅳ.路由器必须实现p协议
while和do-while循环的主要区别是()。
最新回复
(
0
)