Before impact, you put energy into the racquet to get it up to speed for the collision, and during the impact you put in a little more energy to aim the shot.

• 击球之前，你在球拍之上加诸能量以便增加击球的速度，击球的过程中，你还得往球拍上加点儿力，以便把球打到目的的方向。