on只是单纯的方向上的上面,而onto则是偏向于表示一个趋向,从什么物体上移动到另一个一个物体上
on指:在……上面.例如: the book was on the desk.onto指的是某物经过某种运动【掉落,落下等】之后才到达某物的上面.例如: rainwater was falling drop onto her clothes from the eaves of a thatched cottage.茅檐下的雨水,一滴一滴的落到衣上来.