题目

This is          story I've told you．Isn’t it          interesting one? A．the；the              B．the；an                C．a；an                    D．a：the 答案：B雨滴从高空由静止落下，若雨滴下落时空气对其阻力随雨滴下落速度的增大而增大，下图中能正确反映雨滴下落运动情况的是 (　　)