题目

— Mrs. Green,do you think I can get an “A” in the final exam if I start working hard now?   — Of course. _________.     A. Better late than never                        B. Many hands make light work     C. You cannot burn the candle at both sides         D. Actions speak louder than words 答案：A质点仅在恒力的作用下，在xOy平面内由坐标原点运动到A点的轨迹如图所示，经过A点时速度的方向与x轴平行，则恒力的方向可能沿 A．x轴正方向            B．x轴负方向   C．y轴正方向            D．y轴负方向