问题 选择题

关于重力的说法中正确的是(  )

A.在落向地球时,物体受的重力大于它静止时受的重力

B.因重力的方向总是竖直向下的,故重力总是和地面垂直

C.重力就是物体对水平桌面的压力

D.在地球的不同纬度地点,同一物体受到的重力大小和方向都不一样

答案

A、重力大小与物体的质量成正比,有G=mg,与速度无关,故A错误;

B、重力的方向总是竖直向下的,故一定垂直水平面,但地面不一定水平,故不一定垂直地面,故B错误;

C、重力是地球对物体的力,压力是物体对地面的力,不是同一个力,故C错误;

D、由于地球是个椭球体,在地球不同纬度的重力加速度略有差异,故在地球的不同纬度地点,同一物体受到的重力大小和方向都不一样,故D正确;

故选D.

单项选择题
阅读理解

From Monday until Friday most people are busy working or studying, but in the evenings and on weekends they are free to relax and enjoy themselves. Some watch TV or go to the movies; others take part in sports. It depends on individual interest. There are many different ways to spend our spare time.

Almost everyone has some kind of hobby. It may be anything from collecting stamps to making model airplanes. Some hobbies are very expensive, but others don’t cost anything at all. Some collections are worth a lot of money; others are valuable only to their owners.

I know a man who has a coin collection worth several thousand dollars. A short time ago he bought a rare fifty-cent piece worth $250!He was very happy about his purchase (buying) and thought the price was reasonable. On the other hand, my youngest brother collects matchboxes. He has almost 600 of them but I doubt if they are worth any money. However, to my brother they are extremely valuable. Nothing makes him happier than to find a new matchbox for his collection.

That’s what a hobby means, I guess. It is something we like to do in our spare time simply for the fun of it. The value in dollars is not important, but the pleasure it gives us is.

小题1:The word “individual” in the first paragraph most probably means        .

A.different

B.strange

C.secret

D.one’s own小题2:According to the passage, most people are          from Monday until Friday.

A.free to relax and enjoy themselves

B.busy working or studying

C.free to take part in sports games

D.busy watching TV and going to the cinema小题3:Something that one enjoys doing in one’s spare time is a          .

A.job

B.pleasure

C.hobby

D.contribution小题4:In the writer’s opinion,             .

A.all hobbies are very expensive

B.some hobbies don’t cost anything

C.hobbies are worthless

D.hobbies are valuable to everybody