有一天 ,学生来告诉我说课本上的一幅图错了 (人教试验版第一册第 81页 ) ,他认为描述伞转动的箭头画反了 ,也就是说伞的转动方向俯视应该是顺时针方向 ,他的理由是 :由于惯性 ,先离开伞的水滴应“拖后”而不会超前 .我告诉他这可能是他的一种错觉 ,因为水滴离开伞后仍保持了水 One day, the students came to tell me that a picture on the textbook was wrong (Personal Education Trial Book No. 1 p. 81). He thought that the arrow describing the umbrella’s rotation was reversed, that is to say, the direction of the umbrella’s rotation should be In clockwise direction, his reason is: Because of inertia, the water drop that leaves the umbrella first should be “dragging behind” without going ahead. I told him that this may be his illusion because the water droplets still keep water after leaving the umbrella.