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
2023-11-14
9
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 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. [br] 【C19】
选项
A、unless
B、when
C、until
D、after
答案
C
解析
根据固定结构搭配:not...until...正确答案是C。
转载请注明原文地址:https://tihaiku.com/zcyy/3185016.html
相关试题推荐
Humanbeingshave______themselvestoverydiverseenvironmentswiththehelpof
Humansareuniqueintheextenttowhichtheycanreflectonthemselvesand
Humansareuniqueintheextenttowhichtheycanreflectonthemselvesand
Humansareuniqueintheextenttowhichtheycanreflectonthemselvesand
Humansareuniqueintheextenttowhichtheycanreflectonthemselvesand
Humansareuniqueintheextenttowhichtheycanreflectonthemselvesand
Humansareuniqueintheextenttowhichtheycanreflectonthemselvesand
Humansareuniqueintheextenttowhichtheycanreflectonthemselvesand
Humansareuniqueintheextenttowhichtheycanreflectonthemselvesand
Humansareuniqueintheextenttowhichtheycanreflectonthemselvesand
随机试题
《城乡规划法》规定,以出让方式取得国有土地使用权的建设项目,在签订国有土地使用权
下列各项与债券相关的因素中,影响债券内在价值的有()。A.市场价格 B.市场
金某,女性,21岁。1周来双侧肩、肘、膝关节游走性疼痛,局部灼热红肿,痛不可触,
高校充分发挥学科综合、人才汇聚的优势,不断创新参与产学研结合的实践模式,为构建国
根据《公安机关督察条例》的规定,督察机构对公安机关及其人民警察可以进行督察的事项
进行现金管理的目的在于( )。A.满足未来消费的需求 B.满足日常的周期性的
下列属于金融市场短期信用工具的有()。A.债券 B.汇票 C.股票 D.本
3月2日,某交易者买入10手5月份A期货合约同时卖出10手7月份该期货合约,价格
(2011年真题)反映沥青混合料受水损害时抵抗剥落能力的指标是()。A.稳定度
某工程双代号网络计划如下图所示,工作E最早完成时间和最迟完成时间分别是()
最新回复
(
0
)