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
57
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.
【C13】
选项
A、though
B、as
C、than
D、and
答案
B
解析
要表示倒装和让步,只有B。
转载请注明原文地址:https://kaotiyun.com/show/WEQK777K
0
专业英语四级
相关试题推荐
Seventy-four-year-oldsarethemost【C1】______peopleinthepopulation,accordingtoanewresearch.Fewerresponsibilities,fina
Seventy-four-year-oldsarethemost【C1】______peopleinthepopulation,accordingtoanewresearch.Fewerresponsibilities,fina
Onceuponatime,youbelievedinthetoothfairy.Youcountedonthestabilityofhousingpricesanddependedonbankerstobe,
Onceuponatime,youbelievedinthetoothfairy.Youcountedonthestabilityofhousingpricesanddependedonbankerstobe,
Whatdoyoulookforinapotentialdate?Sincerity?Goodlooks?Character?Conversationalability?Askedto【C1】______suchquali
Incontrasttologic,thereiscommonsense,orstillbetter,theSpiritofReasonableness.IthinkoftheSpiritofReasonablen
Togiveyouageneralideaofourproducts,weenclosethecataloguesshowingvariousproductshandledbyuswithdetailedandm
WhichofthefollowingisNOTmentionedasahelpininterviews?
Inthe1920sdemandforAmericanfarmproductsfell,asEuropeancountriesbegantorecoverfromWorldWarIandinstitutedaust
Inthe1920sdemandforAmericanfarmproductsfell,asEuropeancountriesbegantorecoverfromWorldWarIandinstitutedaust
随机试题
在建筑物的进线处将PE干线、设备PE干线、进水管、采暖和空调竖管、建筑物构筑物金属构件和其他金属管道、装置外露可导电部分等相联结,此措施称为()。
色氨酸转运异常导致的皮肤综合征是
造血干细胞的免疫标记是
传染性单核细胞增多症
中央银行的性质包括()。
甲公司与乙运输公司签订了多式联运合同,应甲要求,乙开具了可转让多式联运单据。甲隐瞒了所运物品为危险物等相关信息,也未履行妥善包装的义务,且不久就将这份合同转让给了丙公司。运输期间该物品发生自燃,导致运输工具损毁。对此,下列说法中正确的是()。
知识是个体通过与环境相互作用后获得的()。
设随机变量X的分布律为P{X=k}=,k=1,2,…,λ>0,则常数c=()。
数据是信息的符号表示或称载体;信息则是数据的内涵,是数据的
TrustMe,I’maRobot[A]Withrobotsnowemergingfromtheirindustrialcagesandmovingintohomesandworkplaces,roboticists
最新回复
(
0
)