题目

 When women sit together to watch a movie on TV, they usually talk simultaneously（同时地）about a variety of subjects, including children, men, careers and what’ s happening in their lives. When groups of men and women watch a movie together, the men usually end up telling the women to shut up. Men can either talk or watch the screen -- they can’ t do both -- and they don’ t understand that women can. Besides, women consider that the point of all getting together is to have a good time and develop relationships -- not just to sit there like couch potatoes staring at the sc重400N的小车，在40N的水平推力作用下，沿水平面前进20m，撤去推力，小车又前进了5m后停下．求：全过程中推力做的功．