两球相向运动,发生正碰,弹性碰撞后两球均静止,于是可以判定,在弹性碰撞以前两球()
A:质量相等
B:速度大小相等
C:动量大小相等
D:以上都不能判定
— What do you think of tomorrow's football match? — _______ difficult for us _______ the match.
vvvvvvvvvvvvv