首页
登录
职称英语
The ability of falling cats to right themselves in midair and land on their
The ability of falling cats to right themselves in midair and land on their
游客
2023-11-19
35
管理
问题
The ability of falling cats to right themselves in midair and land on their feet has been a source of wonder for ages. Biologists long regarded it as all example of 【C1】______ by natural selection, but for physicists it bordered on the miraculous. Newton’s laws of motion 【C2】______ that the total amount of spin of a body cannot change 【C3】______ an external torque speeds it up or slows it down. If a cat has no spin when it is released and experiences no external torque, it ought not to be able to 【C4】______ as it falls. In the speed of its execution, the 【C5】______ of a tumbling cat resembles a magician’s trick. The gyrations of the cat in midair are 【C6】______ fast for the human eye to follow, so the process is obscured. 【C7】______ the eye must be speeded up, or the cat’s fall slowed down for the phenomenon to be observed. A century ago the former was accomplished 【C8】______ high-speed photography using equipment now 【C9】______ in any pharmacy. But in the nineteenth century the 【C10】______ on film of a falling cat constituted ascientific experiment. The experiment was described in a paper presented to the Paris Academy in 1894. Two sequences of twenty photographs 【C11】______ one from the side and one from behind, 【C12】______ a white cat in the act of righting itself. Grainy and quaint 【C13】______ they are, the photos show that the cat was dropped upside down, with no initial spin, and still landed on its feet. Careful analysis of the photos reveals the secret. As the cat rotates the front of its body 【C14】______ , the rear and tail twist counterclockwise, 【C15】______ the total spin remains zero, 【C16】______ Newton’s laws. Halfway down, the cat pulls in its legs before reversing its twist and them extends them again, 【C17】______ he desired end result. The explanation was that while no body can acquire spin without torque, a flexible one can readily change its 【C18】______ . Cats know this instinctively, but scientists could not be sure how it happened 【C19】______ they increased the speed of their 【C20】______ a thousand fold. [br] 【C7】
选项
A、Neither
B、Never
C、Either
D、Whether
答案
C
解析
本句的意思是:要观察到这一现象,要么使眼睛看事物的速度加快,要么使猫的下降速度放慢,根据either...。r...的意思,排除A、B和D。
转载请注明原文地址:https://tihaiku.com/zcyy/3201343.html
相关试题推荐
Hit-hikersmusthavetakegreatpainstomakethemselves______soastoarrestt
Theywillneverreconcilethemselvesto______.A、defeatB、theirdefeatC、bedefe
Dreamsare__________inthemselves,but,whencombinedwithotherdata,theyca
Inancienttimespeoplewhowerethoughttohavetheabilityto________dreams
Whenworkerspushtogethertoorganizethemselvesintradeunions,employersfin
Theywillneverreconcilethemselvesto________.A、defeatB、theirdefeatC、bede
[originaltext]Inadditiontothesegeneralthreatstostabilityandsecuri
Husbandandwifewithacommondutytothecountrywillfindthemselves______cl
Noonecandenythatpesticidehaveimprovedtheabilityoffarmerstobrin
Noonecandenythatpesticidehaveimprovedtheabilityoffarmerstobrin
随机试题
______Chinaismobilizedtogoallouttobuildthecountryintoapowerful,mod
(浙江大学2008年试题)Theenergycrisis,whichisbeingfeltaroundtheworld,hasd
A.techniqueB.processesC.testedD.procedure
IsHigherEducationaBubble?MycolleagueatDemocracy
虚拟现实的交互能力依赖于()的发展。A、立体显示技术 B、实时三维图形生
下列关于医疗机构配制制剂管理的叙述,错误的是( )。A.凭医师处方在本医疗机构
Thechangeinthatvillagewasmiraculou
下列关于贷款担保作用的说法,错误的是()。A.协调和稳定商品流转秩序,促进国民
下列有关劳动合同争议解决的说法正确的是:()A.劳动者与用人单位就解除或者
常用于表面麻醉的是( )。A.丁卡因 B.丁哌卡因 C.利多卡因 D.普
最新回复
(
0
)