问题 选择题

下列说法正确的是(  )

A.抛向空中的球,在空中运动时受到重力和抛力的作用

B.武术运动员训练时,用力冲拳没有打到物体,说明力可以没有受力物体.

C.冰球被击后在冰面上滑行,滑行过程中由于受到冰面对它阻力作用而慢慢停下来

D.只有有生命或有动力的物体才会施力,无生命或无动力的物体只会受到力,不会施力

答案

A、抛向空中的球,在空中运动时只受到重力的作用.由于手与球不再接触,所以球不再受到抛力.故A错误.

B、武术运动员训练时,用力冲拳没有打到物体,不能说明力可以没有受力物体,手臂对拳头有力的作用,拳头是受力物体.故B错误.

C、冰球被击后在冰面上滑行,冰面对它的阻力起减速作用,使它慢慢停下来.故C正确.

D、由于力的作用是相互的,不管什么物体,是受力物体的同时也一定是物力物体.故D错误.

故选C

单项选择题
单项选择题

When Dave was eighteen, he bought a secondhand car for 200 so that he could travel to and from work more (1) than by bus. It worked quite well for a few years, but then it got so old, and it was costing him (2) much in repairs that he decided that he had better (3) it.

He asked among his friends to see if anyone was particularly (4) to buy a cheap car, but they all knew that it was falling to pieces, so (5) of them had any desire to buy it. Dave’s friend Sam saw that he was (6) when they met one evening, and said, "What’s (7) , Dave"

Dave told him, and Sam answered, "Well, what about advertising it in the paper You may (8) more for it that way than the cost of the advertisement!" Thinking that Sam’s (9) was sensible, he put an advertisement in an evening paper, which read "For sale: small car, (10) very little petrol, only two owners. Bargain at 50. " For two days after the advertisement first appeared, there was no (11) . But then on Saturday evening he had an enquiry. A man rang up and said he would like to (12) him about the car. "All right, " Dave said, feeling happy. He asked the man whether ten o’clock the next morning would be (13) or not. "Fine, " the man said, "and I’ll (14) my wife. We intend to go for a ride in it to (15) it. "

The next morning, at a quarter to ten, Dave parked the car in the square outside his front door, (16) to wait there for the people who had (17) his advertisement. Even Dave had to (18) that the car really looked like a wreck. Then, soon after he had got the car as clean (19) it could be, a police car stopped just behind him and a policeman got out. He looked at Dave’s car and then said, "Have you reported this (20) to us yet, sir\

20()

A.bargain 

B.sale 

C.accident 

D.result