在图所示的四种情境中，人对物体做功的是：（ ）
答案：B
题目分析：B推动小车时，对车的推力向前，车通过的距离向前，符合做功的两个必要因素，故对车做功，符合题意；
ACD选项中，都是只有力而没有在力的方向上通过距离，不做功，不符合题意．
故选B．
点评：判断是否做功要明确三种情况不做功：一是有力无距离（例如：推而未动），二是有距离无力（靠惯性运动），三是力的方向与运动方向垂直．
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| In Australia, different people have different ways to enjoy themselves. They also have their own ideas about __1__ to pass time. __2__ children, about 80%, work hard in school because they have to take lots of exams. After school, they don't want to stay at home reading books any more. __3__, they put aside their school bags and go out to play. Some old people __4__ early in the morning. Then they go to the park to __5__. It helps them know what is happening around the world. In the evening, they would prefer to stay at home __6__ rather than do anything else. Young people enjoy having __7__ trips on weekends. They go to mountains to have a picnic or go to the __8__ to camp. They usually start on Friday and spend one or two days outside. Then on __9__ evening, they start their way back home. __10__ seems to be in a hurry, although a busy week is waiting for them again. | ||||
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