问题 选择题

关于万有引力和万有引力定律理解正确的有(  )

A.不可能看作质点的两物体之间不存在相互作用的引力

B.可看作质点的两物体间的引力可用F=G

m1m2
r2
计算

C.由F=G

m1m2
r2
可知,两物体间距离r减小时,它们之间的引力增大,紧靠在一起时,万有引力非常大

D.引力常量的大小首先是由安培测出来的,且等于6.67×10-11N•m2/kg2

答案

A、任意两个物体间都存在相互作用的引力.故A错误.

    B、万有引力定律的公式F=G

m1m2
r2
适用于质点间的万有引力.故B正确.

    C、由F=G

m1m2
r2
可知,两物体间距离r减小时,它们之间的引力增大,当r小到一定程度,物体不能看成质点,公式不再适用.故C错误.

    D、引力常量是卡文迪许测量出来的.故D错误.

故选B.

单项选择题
单项选择题

It seems incredible to me that Latin is not taught in schools as a matter of course, especially in a country that is forever lamenting its own (undeniable) mediocrity when it comes to speaking foreign languages. As a 13-year-old, I hardly approached my own Latin lessons with anything resembling enthusiasm—I might have been keener if Aeneas went to the shops occasionally—but I am terrifically grateful I had them, all the same.
The benefits are many. Having a basic grounding in Latin makes learning Romance languages a doodle(轻而易举的事): the fact that I speak English plus three others has less to do with any genetic predisposition—I was hopeless at learning Russian—than with an understanding of the root and provenance of Latin-derived words.
It would be impossible to have a smattering of Latin and find oneself stuck in Italy, provided one managed to persuade the speaker to slow down a bit. And the reason I can (arguably) just about string a sentence together in English—which isn’t my first language—has a great deal to do with understanding, through Latin, the way sentences and grammar work.
Latin also has its own pleasing internal logic: you follow the rules and you get the answer. And I really believe that if you know Latin, you half-speak French already. The British used not to be appalling at languages: my theory is that they only became so during the past century, when Latin stopped being widely taught.
Detractors(恶意批评者) might point out that there is little use in learning a dead language. But Latin is not dead: it’s everywhere. It makes the kind of people who never use two short words when six big ones will do intelligible. It demystifies jargon and legalese. It helps with crosswords. It even forces those of us who are pathologically illogical to think logically every once in a while: I remember the pleasure I felt at school, during Latin translation, when I realized I could create order and sense out of apparent chaos.
Really, Latin’s useful applications are manifold. Watching Who Wants To Be A Millionaire a few weeks ago, I noticed that the question which felled the contestant would almost certainly not have stumped him had he had some Latin. Of all the possible answers, only one had a Latin root that echoed the question. From Cicero to Chris Tarrant in a few easy steps, you can’t say more modem or less dusty than that.

The word "a smattering" underlined in Paragraph 3 is closest in meaning to ______.

A.a little knowledge

B.a lot

C.plenty of

D.little knowledge