问题 选择题

某同学用水平力推放在水平桌面上的饮料瓶的底部,饮料瓶桌会沿桌面滑动;当他用同样大小的水平力推饮料瓶的瓶盖部位时,饮料瓶并没有滑动而是发生了翻到.这个事例说明力的作用效果(  )

A.与力的大小有关

B.与力的作用点有关

C.与力的方向有关

D.与受力面积有关

答案

用水平力推放在水平桌面上的饮料瓶的底部,饮料瓶桌会沿桌面滑动;当他用同样大小的水平力推饮料瓶的瓶盖部位时,饮料瓶并没有滑动而是发生了翻到.力的大小和方向相同,力的作用点不同,力的作用效果不同.

故选B.

完形填空

Ali is from a Middle Eastern country. He now stays in the USA. He smokes a lot of cigarettes every day. He has smoked for nine years. Ali says, “ I tried to quit (放弃) smoking in my hometown, but it was impossible. My parents smoke. My brothers smoke. All my friends smoke. At parties and at meetings, almost all the men smoke. Here in the United States, not as many people smoke.  ____小题1:____ ”

Many smokers are like Ali: they want to stop smoking.  ____小题2:____  They know it can cause cancer and heart disease. But it is difficult for them to give up smoking because cigarettes have a drug in them. The drug is nicotine. People who smoke a lot need nicotine.

____小题3:____  The nicotine makes him sick. In a few days, the smoker’s body is used to the nicotine, and he feels fine. Later, the smoker needs nicotine to keep feeling fine. Without nicotine, he feels bad.

___小题4:____  Many people who quit will soon smoke again. At a party or at work they will decide to smoke “just one” cigarette. Then they will smoke another cigarette, and another. Soon they become smokers again.  __小题5:____

A.It is very hard to quit smoking.

B.It will be easier to change the smoking habit here.

C.Thus nicotine makes smokers addicted to cigarettes.

D.The smokers know that smoking is bad for their health.E. When a person first begins to smoke, he usually feels terrible.

F. Maybe there is only one easy way to quit smoking: never start.

G. But it is said that medicine is needed to stop them from smoking.

多项选择题