问题 选择题

关于共点力,下面说法中不正确的是(  )

A.几个力的作用点在同一点上,这几个力是共点力

B.几个力作用在同一物体上的不同点,这几个力一定不是共点力

C.几个力作用在同一物体上的不同点,但这几个力的作用线或作用线的延长线交于一点,这几个力也是共点力

D.物体受到两个力作用,当二力平衡时,这两个力一定是共点力

答案

A、几个力的作用点在同一点上,这几个力是共点力,故A正确;

B、几个力作用在同一物体上的不同点,但它们的延长线或反向延长长交于一点,这几个力也是共点力,故B错误,C正确;

D、物体受到两个力作用,当二力平衡时,这两个力一定是共点力,故D正确;

本题选择错误的,故选:B.

阅读理解

I still remember my first night as a young policeman.

It was a cold and wet night. Over the radio came the message to deal with an accident in one of the side streets of the city. The scene of the accident wasn’t far away and we arrived after 10 minutes. Two cars had crashed. Two women were lying on the street and one driver was still in the car. The driver was quite drunk(喝醉) and kept shouting to us. He didn’t get badly hurt. A young woman died at once when the two cars crashed. I was holding the other woman and tried to stop the bleeding, but at last I had to watch her die in my arms.

Three months later, I saw the driver in court and found him to be a normal person. He was sorry for his actions. In the end, he was put into the prison for several years. A man isn’t a man if he drinks 10 beers in an hour. A man is a man when he knows his limit and takes responsibility(责任). When he can stay away from wine, he can drive more safely.

小题1:What was the writer asked to do on his first night as a young policeman?

A.To drink with friends.

B.To tell a story on the radio.

C.To meet two women.

D.To deal with a traffic accident.小题2:We know _____ died in the accident.

A.the man

B.one woman

C.two women

D.nobody小题3:At that time, the man driver was_____.

A.drunk

B.badly hurt

C.happy

D.singing小题4:At last, the driver _____.

A.went home

B.was put into the prison

C.took the two women to hospital

D.died in the accident小题5:In the writer’s opinion, a man can’t drive _____.

A.with two women

B.after drinking wine

C.on a cold and wet night

D.if he doesn’t drink 10 beers in an hour

单项选择题