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
36
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.
【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...or... 的意思,排除A、B和D。
转载请注明原文地址:https://kaotiyun.com/show/CEQK777K
0
专业英语四级
相关试题推荐
Itisnoteasytopin-pointthe【C1】______oftheChristmasfeast,todaythemostimportantfeastoftheChristmasseasoninmost
Signhasbecomeascientifichot【C1】______.【C2】______inthepast20yearshavespecialistsinlanguagestudyrealizedthatsigne
Seventy-four-year-oldsarethemost【C1】______peopleinthepopulation,accordingtoanewresearch.Fewerresponsibilities,fina
Accordingtothepassage,mothersin______spendmoretimelookingafterchildren.
WhichofthefollowingisNOTthereasonthatthemanwantstogoonadiet?
Decidewhichofthechoicesgivenbelowwouldbestcompletethepassageifinsertedinthecorrespondingblanks.Mostworthw
Decidewhichofthechoicesgivenbelowwouldbestcompletethepassageifinsertedinthecorrespondingblanks.Mostworthw
Openupmostfashionmagazinesandyouwillseeincrediblythinmodelswithimpossiblehairandwearingunreasonablyexpensive,
Openupmostfashionmagazinesandyouwillseeincrediblythinmodelswithimpossiblehairandwearingunreasonablyexpensive,
Thedesegregationwasachievedthroughanumberofstruggles,_____havebeenmentionedinpreviouschapters.
随机试题
只要可燃物浓度在爆炸极限之外就是安全的。()
九味羌活汤中的臣药是
可以销售非国家强制免疫用生物制品的单位为()
通常所说的“利不生利”的计息方法是( )。
某进口产品到岸价按照外汇牌价折算成人民币为60万元,应缴纳进口关税4.8万元。若消费税为15%,则应缴纳消费税税额为()万元。
郑爽是一名刚毕业不久的社会工作专业的研究生,她立志在社会工作中作出一番成就,于是成立了一个从事青少年服务的非政府组织,她通过多种途径获得了机构运行的资金。下列不属于机构资金来源的是()。
有的人“大器晚成”,而有的人“少年得志”,这体现了个体身心发展的()规律。
栉风:沐雨
实施BSP研究的主要活动中应包括多项活动内容,其中最基础的活动是()。Ⅰ.定义企业过程Ⅱ.定义数据类Ⅲ.成果报告Ⅳ.定义信息结构
Economy,oneoftheprinciplesofsuccessinthedetailsofhousekeeping,consistsnotalone【C1】______makingadvantageoususe
最新回复
(
0
)