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
2010-02-17
35
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 a scientific 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 thousandfold.
【C12】
选项
A、showed
B、shows
C、show
D、had shown
答案
C
解析
照片虽然摄于1894年,但现在仍存在,因此用现在时,而且主语是复数,故选C。
转载请注明原文地址:https://jikaoti.com/ti/RYbMFFFM
0
专业英语四级
相关试题推荐
Whetheryou’retheCEOofaFortune500company,orateenageentrepreneurjuststartingout,communicationskillsarevitally
Thesedays,sciencemayhavedissectedalmosteveryelementofourdiet,butmanyofusstillfeelatthesea.Evenwhensticki
Secondlanguageteachingshouldfocusonencouragingacquisition,andonprovidinginputthatstimulatestheconsciouslanguage
ThehistoryofindigenouseducationprovisionthroughoutAustralia’sremoteareasisrepletewithinstancesofneglect,infras
Nottoshowill-feelingabouthisproposal,I______followedhimdownagaininfourorfiveminutes.
Mostofthemembersmadesucha______protestagainsttheproposalthatthecommitteehadtoyield.
Thishousewillprobablycomeonthe______nextmonth.
Booknow. CallHiltonReservationsWorldwide,toll-freefromyourcountry BeijingandShanghai,China—108006508091,Hong
OnNewYear’sEve,therewillbeafirework______atPeople’sSquare.
Jealousytypicallyreferstothethoughts,feelings,andbehaviorsthatoccurwhenapersonbelievesavaluedrelationshipisbe
随机试题
桑叶的作用偏于
村庄规划要依据经过法定程序批准的镇总体规划或乡总体规划,同时也要充分考虑所在村庄的实际情况,在此基础上,对村庄的各项建设做出具体的安排。村庄规划编制内容为()
常用水泥的技术要求主要包括()。
使用总账系统,输入科Et编码时,错误的是()。
下列各项中,说法不正确的是( )。
根据《票据法》的规定,支票的类型有()。
根据公司法律制度的规定,有限责任公司股东对股东会特定事项作出的决议投反对票的,可以请求公司按照合理的价格收购其股权,退出公司。下列属于该特定事项的有()。
甲某欠乙某1千元钱,甲某以4辆自行车抵押给乙某,并签定合同。次日,甲某、乙某去有关部门办理抵押登记手续,由于两人疏忽,漏登记2辆。下列对本案中的抵押行为说法正确的是( )。
求∫0nπ|cosx|dx.
[A]Monitoryouralcoholuse[B]Payattentiontotablemanners[C]Don’tbeagossip[D]Networkwithhigher-ups[
最新回复
(
0
)