Dynamics is a branch which deals with the study of the forces ___ on ___ objects.
问题描述：
Dynamics is a branch which deals with the study of the forces ___ on ___ objects.
A.acted,moving B.acting,moving,应该是选B,可是为什么呢,因为act是力本身做出的动作么?我现在是这么理解的.
答
作用于移动中物体的力.主动.