题目

There are rules in our school. I can't stand some of them. A . too much B . too many C . much too D . many too 答案：B一物体做匀变速直线运动，在2s内从8m/s减少到4m/s，方向不变，则物体的加速度的大小为  （      ） A、4m/s2        B、6m/s2        C、2m/s2       D、3m/s2