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. Biolo
The ability of falling cats to right themselves in midair and land on their feet has been a source of wonder for ages. Biolo
admin
2009-01-05
23
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 speeded up, or the cat’s fall slowed down for the phenomenon to be 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 then 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.
【C17】
选项
A、to
B、as
C、for
D、with
答案
D
解析
转载请注明原文地址:https://jikaoti.com/ti/WQXMFFFM
0
专业英语四级
相关试题推荐
PositiveforYouthaimstoplaceteenagersandyoungpeopleatitsheart.Thereistheaccurateexpectationteenagersthemselves
PositiveforYouthaimstoplaceteenagersandyoungpeopleatitsheart.Thereistheaccurateexpectationteenagersthemselves
PositiveforYouthaimstoplaceteenagersandyoungpeopleatitsheart.Thereistheaccurateexpectationteenagersthemselves
Formany,thepursuitofhappinessisalsothepursuitofprosperity.PartoftheAmericandreamistheabilitytoprovide【M1】__
Formany,thepursuitofhappinessisalsothepursuitofprosperity.PartoftheAmericandreamistheabilitytoprovide【M1】__
Formany,thepursuitofhappinessisalsothepursuitofprosperity.PartoftheAmericandreamistheabilitytoprovide【M1】__
Formany,thepursuitofhappinessisalsothepursuitofprosperity.PartoftheAmericandreamistheabilitytoprovide【M1】__
Formany,thepursuitofhappinessisalsothepursuitofprosperity.PartoftheAmericandreamistheabilitytoprovide【M1】__
随机试题
向上级机关的请示的生效时间是()
设矩阵A,B为可逆方阵,其行列式分别为|A|,|B|.则下列各式中,正确的是().
A.肌梭的传入冲动增加,腱器官的传入冲动减少B.肌梭的传入冲动减少,腱器官的传入冲动增加C.肌梭的传入冲动增加,腱器官的传入冲动增加D.肌梭的传入冲动减少,腱器官的传入冲动不变E.肌梭的传入冲动不变,腱器官的传入冲动增加当骨骼肌作等张收缩时
围产期保健原则中哪项是正确的()
下列情况下,不需要洗手的是
在处理税法对人的效力时,我国税法采用()原则。(2006年)
根据以下资料,回答下列问题。2012年1~6月,江西省十大战略性新兴产业固定资产投资(以下简称“十大产业投资”)总量突破千亿元,达1112.52亿元,比上年同期增长24.0%,占全省固定资产投资(计划投资500万元及以上项目固定资产投资,下同)的23.5
(2010福建)一只蚂蚁从下图的正方体的A顶点沿正方体的表面爬到正方体的C顶点,设正方体边长为a,则该蚂蚁爬过的最短路程为:
ResultingfromthebombingoftheWordTradeCenter,AmericansfearedthattheywouldbeattackedbythenationshostiletoAmer
A、Tourguideandguest.B、Friends.C、Colleagues.D、Teacherandstudent.A判断题。这位女士一直在给这位男士介绍华盛顿这一城市,因此可以判断这位女士是导游,而这位男土是游客,所以应选A。
最新回复
(
0
)