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
A、A bat caught the insect in midair and ate it. B、Dolphin’s clicking sounds bounced off the fish and back to it. C、A person hear
A、A bat caught the insect in midair and ate it. B、Dolphin’s clicking sounds bounced off the fish and back to it. C、A person hear
admin
2016-11-26
80
问题
Objects that are vibrating make sounds. Rhythmic sound vibrations produce sound waves which travel in every direction. The frequency of a sound is the number of waves that pass a given point each second. The more rapidly an object vibrates, the greater the frequency of sound it makes. Frequency is measured in hertz. One hertz equals one sound wave per second. The frequency of sound determines the degree of highness or lowness of the sound. A high-pitched sound has a higher frequency than a low-pitched sound. Humans hear sounds that have frequencies from about 20 hertz to 20,000 hertz. Sound with a frequency higher than 20,000 hertz is called ultrasound which is too high-pitched for humans to hear. However, many animals can hear ultrasound. Bats can hear higher sounds than any other animal. Some can hear up to 210,000 hertz. Bats send out lots of high-pitched squeaks and then listen to the echoes bouncing off things like insects. The shorter the time interval between the squeak and the echo, the closer they are to the insect. Using sound to find or "see" things is called echolocation. Another animal that uses ultrasound is the dolphin. Dolphins can hear sounds up to about 150,000 hertz. Dolphins use sound waves to find food underwater. They make clicking sounds that hit whatever is around them and then bounce back to the dolphins. Dolphins can send as many as 2,000 clicks per second. Dolphins’ ultrasound ability is so sensitive that they can detect small fish from 10 feet away.
9. What is the relationship between the vibration of an object and the frequency of its sound?
10. What sounds can humans hear?
11. According to the speaker, what is the phenomenon of echolocation?
选项
A、A bat caught the insect in midair and ate it.
B、Dolphin’s clicking sounds bounced off the fish and back to it.
C、A person heard an echo when he shouted into the valley.
D、A dog heard his owner’s whistle because he used ultrasound.
答案
B
解析
细节题。录音提到,用声音来找或看东西被称为“回声定位法”。之后,短文以海豚为例说明“回声定位法”:海豚会发出尖利的声音,这种声音会撞击到它周围的任何物体,然后通过声波形式再传回到海豚处。通过这种方法,海豚可以找到离自己10英尺以内的小鱼。蝙蝠只是利用回声定位原理“找到”食物,但并非caught或ate,所以可排除强干扰项A。
转载请注明原文地址:https://kaotiyun.com/show/lGF7777K
0
大学英语六级
相关试题推荐
科举考试(Keju)是中国古代人才选拔的一种方式。由于采用分科目选举人才的办法,所以叫作科举。隋炀帝于公元605年开设进士科(theimperialexaminationsystem),用考试办法来选拔人才,这标志着科举制度的形成,它把读书、考试和做
起源于举世闻名的道家哲学的道教是中国的本土宗教,建立于东汉时期(公元24~220年),已有1800多年的历史。在封建社会时期,和佛教一样,道教对中国的经济、文化、政治思想产生了巨大的影响,是当时封建统治阶级推崇的主流思想意识之一。道教后来传播到了日本和东
RainforestCity[A]Apatchoftropicalrainforesthastwicethenumberofmammalspecies,fivetimesthebatsandbirdsandten
A、Theyshouldadapttotheneedofthepresentsociety.B、Theyshouldteachchildrentobeawareofsocialproblems.C、Theyshou
Earlierstudieshavetiedchronicsleepdisordersandlowlevelsofsleeptogreaterrisksofheartdiseaseandobesity,andeve
Theriskofdepressionforpeoplewholivealoneisalmost80percenthigherthanforpeoplewholivewithfamilyorroommates.
A、Theman’spersonalexperienceinmilitaryservice.B、Theman’stravelexperienceinAsiabytrain.C、Theman’stravelexperien
A、Domesticviolence.B、Drugoverdoses.C、Highestdiabetesrate.D、Highercaloricintake.B事实细节题。本题问的是文中提到了什么致命伤害的风险。短文中提到,报告中指出美
A、Shelostalotofweightintwoyears.B、Shestoppedexercisingtwoyearsago.C、Shehadauniquewayofstayinghealthy.D、Sh
A、WhattheUSpatentsystemwasabout.B、HowtheUSpatentsystemencouragedtechnologyandcreativity.C、HowtheUSpatentsyst
随机试题
作为中国共产党和社会主义事业指导思想的马克思主义是指
小明是小学四年级学生,对学习不感兴趣,常因学习成绩不好而受到教师和父母的责备;但小明却热衷于玩电脑游戏,经常废寝忘食,并被同伴称为“电脑高手”。试分析:(1)小明为什么爱玩电脑而不爱学习?请用成就动机的理论解释这一现象。(2)教师和家长应如何帮助小明提
他励式直流发电机,励磁绕组除用另外一台小型直流发电机供电外,还可以用整流器供电。()
炮制含苷类药物时应注意
关于脆性x综合征临床表现不正确的是
甲在某银行的存折上有4万元存款。某日,甲将存款全部取出,但由于银行职员乙工作失误,未将存折底卡销毁。半年后,甲又去该银行办理存储业务,乙对甲说:“你的4万元存款已到期。”甲听后,灵机一动,对乙谎称存折丢失。乙为甲办理了挂失手续,甲取走4万元。甲的行为构成何
因购货预付给供应单位的款项属于货币性资产。()
下列单位中属于消费税纳税义务人的是()。
下列关于全陪接团后首次讲解内容的说法中,正确的有()。
根据以下资料,回答下列问题。某年度某机构关于中国宠物主人消费行为及倾向调查回收的10680份有效问卷显示:女性养宠者占58.1%,宠物主人为“80—90后”占79.5%。将宠物定义为“孩子”“亲人”“朋友”和“宠物”的分别为54.5%、33.4%
最新回复
(
0
)