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
The ability of falling cats to right themselves in midair and land on their feet has been a source of wonder for ages. Biologist
The ability of falling cats to right themselves in midair and land on their feet has been a source of wonder for ages. Biologist
admin
2013-04-22
30
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 an 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】______ the 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.
【C8】
选项
A、by means of
B、by way of
C、in the way of
D、not by
答案
A
解析
by means of意思是“通过、借助”,其他选项不符合题意。
转载请注明原文地址:https://kaotiyun.com/show/REQK777K
0
专业英语四级
相关试题推荐
Seventy-four-year-oldsarethemost【C1】______peopleinthepopulation,accordingtoanewresearch.Fewerresponsibilities,fina
Didyousleepwelllastnight?Ordidyouwakeupfeelingfatiguedandsluggish—perhapsevenwonderingifyoureallysleptat
Whatdoyoulookforinapotentialdate?Sincerity?Goodlooks?Character?Conversationalability?Askedto【C1】______suchquali
Incontrasttologic,thereiscommonsense,orstillbetter,theSpiritofReasonableness.IthinkoftheSpiritofReasonablen
Accordingtothepassage,theaverageageofthefleetofDelta/Northwestis______.
Accordingtothepassage,FrenchwomenarenotmentionedleadingEuropeas______.
WhichofthefollowingisNOTmentionedasahelpininterviews?
Whichoneisnottrueabouttheastronautmentionedinthenews?
Whichisnotmentionedinthepassageasanaspectthatfarmingactivitiesaredamaging?
随机试题
驾驶员长期处于紧张状态,会造成神经功能紊乱,最易患()。
上级行政主管部门的工作人员在施工现场检查工作时,应由( )对他们的工作安全负责。
架空导线连接正确的是()。
在国际上,业主方项目管理的方式有多种可能,在以下描述中,正确的是()。
公司股票首次公开发行前,证监会审核员应督促()提供会后重大事项说明。
Hamletisjustan______characterinthenovel.
“近朱者赤,近墨者黑”体现了影响儿童身心发展因素的遗传决定论观点。()
在研究“高校青年教师职业发展状况”时,研究者将受访教师请在咖啡馆中,边喝咖啡边聊天。且告诉青年教师“不要受拘束,没有特定的限制,所有资料都是做研究之用,并为老师保密”。这一访谈是
A、WatchingtheadvertisementofthecompanyonTV.B、Consultingpeoplewhoworkinthecompany.C、Askingtheirfriendstofindo
Veryoldpeopledoraisemoralproblemsforalmosteveryonewhocomesintocontactwiththem.Theirvalues,thiscan’tbe【B1】___
最新回复
(
0
)