问题 多选题

关于合力和分力的大小关系,下列说法正确的是(  )

A.合力必比分力大

B.合力至少比某一个分力大

C.合力可以比任意分力都小

D.合力可以和两个分力的大小相等

答案

A、当二力反向时,合力等于二力大小之差,合力有可能小于分力,故A错误;

B、如果两个分力大小相等、方向相反时,两个力的合力为零,合力小于每一个分力,故B错误;

C、当两个分力大小相等方向相反时,合力等于0,合力小于任意分力,故C正确;

D、当两个分力大小相等,夹角为120°时,合外力和两个分力的大小相等,故D正确;

故选CD.

单项选择题
阅读理解

It is not unusual for people to speak two or three languages; they’re known as bilinguals or trilinguals. Speakers of more than three languages are known as polyglots. And when we refer to people who speak many languages, perhaps a dozen or more, we use the term hyper-polyglot.

The most famous hyper-polyglot was Giuseppe Mezzofanti, a 19th century Italian cardinal, who was said to speak 72 languages. This claim sounds absurd. If you assume each language had 20,000 words, Mezzofanti would have to learn a word a minute, six hours a day, for eleven years—an impossible task. But Mezzofanti was tested by critics, and they were all impressed.

Did Mezzofanti have an extraordinary brain? Or are hyper-polyglots just ordinary people with ordinary brains who manage to do something extraordinary through hard work?

U.S. linguist Stephen Drashen believes that outstanding language learners just work harder at it and then they acquire unusually strong language ability. As an example, he mentions a Hungarian woman who worked as an interpreter during the 20th century. When she was 86, she could speak 16 languages and was still working on learning new languages. She said she learned them mostly on her own, reading fiction or working through dictionaries or textbooks.

Some researchers argue to the contrary. They believe that there is such a thing as a talent for learning languages. In the 1930s, a German scientist examined parts of the preserved brain of a hyper-polyglot named Emil Krebs, who could speak 60 languages fluently. The scientist found that the area of Krebs’s brain called Broca’s area, which is associated with language, looked different from the Broca’s area in the brains of men who speak only one language. However, we still don’t know if Krebs was born with a brain ready to learn dozens of languages or if his brain adapted to the demands he put on it.

Although it is still not clear whether the ability to learn many languages is in born, there’s no doubt that just about all of us can acquire skills in a second, third, or even fourth language by putting our mind to it.

小题1:What does the underlined sentence imply?

A.Mezzofanti could remember 360 words a day.

B.Mezzofanti had a special way to learn languages.

C.Mezzofanti’s achievement was ridiculous.

D.Mezzofanti language ability was astonishing.小题2:The Hungarian woman became a hyper-polyglot mainly because of her __.

A.good memory

B.hard work

C.unique brain

D.learning methods小题3:The German scientist’s findings showed that Krebs ___.

A.had an unusual brain

B.was born with great talent

C.had worked hard at languages

D.expected too much of himself小题4:The author seems to agree that ___.

A.it is not hard to learn foreign languages

B.hard work plays a part in language learning

C.there is no such thing as a talent for languages

D.hyper-polyglots have an inborn talent for language