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
52
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.
【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意为“通过,借助”,其余几个选项的意思不和题意。
转载请注明原文地址:https://jikaoti.com/ti/YYbMFFFM
0
专业英语四级
相关试题推荐
Thedestructionofournaturalresourcesandcontaminationofourfoodsupplycontinuetooccur,largelybecauseoftheextreme
Thedestructionofournaturalresourcesandcontaminationofourfoodsupplycontinuetooccur,largelybecauseoftheextreme
WhichofthefollowingisNOTtrueabouttheAUpeacekeepingforce?
He_______inJapanasheleftbyboatlastmonth.
Generallyspeaking,aBritishiswidelyregardedasaquiet,shyandconservativepersonwhois【C1】______onlyamongthosewith
Thereductionof______UNpeace-keepingtroopswithin3monthsfromRwandaisauthorized.
What’stheprobablerelationshipbetweenthetwospeakers?
Urbancongestionwouldgreatlyberelievedifthe________chargedonpublictransportWeremorereasonable.
Yesterday’sstrikecausedthemostconfusionfor______.
PerhapsthemostheatedargumentacrosstheUnitedStatestodayisthedeathpenalty.Manyarguethatitisan【C1】______deterr
随机试题
关于新发布的《处方管理办法》叙述错误的是
在1930年6月30,我国公布了()。
水运工程单位工程概、预算费用包括()等。
根据我国《诉讼费用交纳办法》的规定,劳动争议案件每件交纳案件受理费()。
关于了解内部控制后对控制风险的评价结论,以下说法中,恰当有()。
心理咨询员与求助者建立良好咨询关系的条件是()。
在以下4个WWW网址中,不符合WWW网址书写规则的是()。
MysonJoeywasbornwithclubfeet.Thedoctorsassuredusthatwithtreatmenthewouldbeabletowalknormally—butwouldneve
DreamFunctionsDreamingisacommonphenomenon.Practicallyallpeopledream,althoughwhethertheycan【1】______themisa
ElvisAaronPresleywasborninatwo-roomhouseinTupelo,MississippionJanuary8,1935.His【D1】______,JessieGarcon,dieda
最新回复
(
0
)