问题 选择题

在研究下述运动时,能被看作质点的物体是(   )

A.研究地球的公转运动;

B.研究乒乓球的旋转效应;

C.研究杂技演员在走钢丝的表演时,杂技演员可以当作质点来处理;

D.研究地球的自转运动。

答案

答案:A

题目分析:研究地球公转时,地球与太阳的距离远大于地球的半径,地球的自转,形状和大小都可以忽略,此时地球可以看成质点,A选项正确;研究乒乓球的旋转效应时,乒乓球的形状、大小和转动都不能忽略,不能看成质点,B选项错误;研究杂技演员走钢丝时,杂技演员的肢体动作对其平衡很关键,不能忽略其大小和形状,C选项错误;研究地球自转时地球形状和大小不能忽略,D选项错误。

阅读理解

Last night I drove a long way (about 500 km) to return home. It was late and I was driving fast because I wanted to get home as soon as possible. So several times when I was driving behind a slow-moving truck on a narrow road, I wanted to shout at the driver ahead.

Then I came to a crossroad with a traffic light. As I drove near, it turned red. I stopped my car at once. I looked left,right and behind. I found no cars or persons — I was alone on the road. The person who would come to the crossroad was at least a mile away in any direction. Certainly going through the light would cause no danger. I could pass the traffic light. But strangely enough, I just stopped there, waiting for several minutes until the light went green. I asked myself why I refused to run the light. Surely it was unnecessary for me to be afraid of danger or being fined (罚款), because there were no cars or police around at all. But I remained waiting until the light changed.

When I finally got home, it was near midnight. My wife had fallen asleep. The question of why I stopped for that light came back to me again, because I stopped another two times for the red lights as “special” as the first one. I stopped, not because of the law, but because it was a good habit I had developed. In fact, we were used to doing something right just because we have made obeying the rules a good habit. We do it just because we should do it. I thought if another man met with the same thing, he would make the same choice. I believed so. And I could be trusted (信任) by others. I believed that everyone would and could control (控制) himself/herself well. It was amazing that we trusted each other to do the right things, wasn’t it?

小题1:When the author drove behind the slow-moving truck, he felt ____.

A.confused but happy

B.sleepy and tired

C.excited but tired

D.angry and worried小题2:Who made the author stopped at the crossroad?

A.A policeman.

B.The author’s wife.

C.The author himself.

D.Another driver.小题3:The author waited until the light went green because ____.

A.running the light would make him fined

B.he was afraid to cause an accident

C.he was prevented by the passers-by

D.he was used to obeying traffic rules小题4:The author is a person who ____.

A.believes others easily

B.can control himself well

C.treats others very unfriendly

D.is very experienced in driving小题5: We can infer from the passage that ____.

A.running the light could help the author get home earlier

B.the author’s wife was angry because he got home late

C.the truck driver in front of the author might be drunk

D.it was very necessary to have very strict traffic rules

单项选择题