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
2021-07-14
37
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/7gJ7777K
0
大学英语六级
相关试题推荐
A、Ithasthemostaggressivepolicies.B、Ithasthehappieststudents.C、Itisaveryexpensiveprivateschool.D、Itislocated
A、Astoryinprose.B、Apoemthatrhymes.C、Atranslationofashortliterarywork.D、Ajournalabouttheprocessofwriting.A
A、Shedidtheassignmentfornextweek.B、Shehadadentistappointment.C、Shewroteashortstory.D、Shefinishedareallystra
A、Collegegraduatesearnmoremoney.B、Thereturnonhighereducationisbad.C、Collegegraduatestendtolosetheirjobs.D、Pur
A、Theambitiontobecomethegreatestmagician.B、Therealitythathefailedinaswimmingrace.C、ThemagicianHoudiniandhis
A、Sheforgotthetime.B、Shedidn’tfeelhungry.C、Sheattendedaprolongedclass.D、Sheranintoanoldfriend.C①从选项可知问题问的是女士的
A、Ahandwrittenone.B、Onethatisrevisedbythestudent.C、Onethatisoriginative.D、Onethatconformstotheinstructions.D
Forthispart,youareallowed30minutestowriteashortessayentitledVillageOfficials.Youshouldwriteatleast150words
Inwhat’sprobablythecraziestheadlineI’veeverwritten,I’vereportedthat【C1】______inlivestockprotectionarehappening
Inwhat’sprobablythecraziestheadlineI’veeverwritten,I’vereportedthat【C1】______inlivestockprotectionarehappening
随机试题
假性糖尿见于
立克次体感染首选哪种药
患者,男性,67岁,突发心跳、呼吸骤停。抢救该患者时,胸外心脏按压的部位是
见证取样和送检次数不得少于试验总次数的()。
企业出售、转让、报废投资性房地产时,不应将所处置投资性房地产的收入计入()。
简述勃拉姆斯的艺术成就及作品风格。
在某公司中,李明帮助了王刚,而王刚帮助了赵贤。李明纳税比赵贤多。由此可以推出()。
影响反应时的因素有()
15周岁的甲获得学校给予的奖学金500元,甲用该笔奖金购买了彩票并获得二等奖3万余元,则甲()。
电子政务的发展大致经历了面向数据处理、面向信息处理和______3个阶段。
最新回复
(
0
)