首页
登录
职称英语
The ability of falling cats to right themselves in midair and land on their
The ability of falling cats to right themselves in midair and land on their
游客
2024-10-27
1
管理
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. [br] 【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://tihaiku.com/zcyy/3819131.html
相关试题推荐
______humanproblemsthatrepeatthemselvesin______liferepeatthemselvesin
Theabilityoffallingcatstorightthemselvesinmidairandlandontheir
Theabilityoffallingcatstorightthemselvesinmidairandlandontheir
Theabilityoffallingcatstorightthemselvesinmidairandlandontheir
Theabilityoffallingcatstorightthemselvesinmidairandlandontheir
Theabilityoffallingcatstorightthemselvesinmidairandlandontheir
Theabilityoffallingcatstorightthemselvesinmidairandlandontheir
Theabilityoffallingcatstorightthemselvesinmidairandlandontheir
Theabilityoffallingcatstorightthemselvesinmidairandlandontheir
Theabilityoffallingcatstorightthemselvesinmidairandlandontheir
随机试题
Iamgoingtoattendtheconference,butyou_______withme.A、needn’ttogoB、d
[originaltext]Theyoungpeoplewhotalkofthevillageasbeing"dead"are
Ⅱ型呼吸衰竭不能给予高浓度吸氧的原因主要是()A. B.诱发呼吸性碱中毒
安全管理目标的主要内容包括()。A.生产安全事故控制目标 B.质量合格目
下列结论中,错误的是:
关于健康年龄的描述正确的是()。A.健康年龄大于自然年龄说明情况危险度低于人
贷款承诺费是指银行对( )的那部分资金收取的费用。A.已承诺贷给客户,客户已经
A.疏肝 B.纳气 C.补气 D.降气 E.破气香附的功效是()
某运维人员在巡视时发现运行中干式电抗器发现电抗器()表面异常过热、冒烟,应立即申
男,45岁。腹部撞伤后脐周疼痛2小时,呈持续性,伴恶心,无呕吐,腹痛范围迅速扩大
最新回复
(
0
)