从分子的角度分析，下列解释错误的是（　　）

如图所示，斜面小车M静止在光滑水平面上，紧贴墙壁．若在斜面上放一物体m．再给m施加一竖直向下的恒力F．M、m均保持静止，则小车受力的个数为（   ）

选择合适的词填空。

      doesn't   chores    make   feed    will    going    wash   set   homework   trash

    Jack has to do some ____ at home this week, because his mom is ____ on a trip to Beijing. Every morning he has to ____his bed but he ____ have to make dinner. He doesn't have to take out the ____, because his father ____ do that. In the evening, Jack has to ____ the table and then ____ the dishes. He doesn't have to ____ his fish but he has to do his ____!