on的读音：英[?n]、美[ɑ?n]。
（1）on作为介词：对、在、根据、使用。例句：（覆盖、附着）在…上（意指接触物体表面或构成物体表面的一部分）in or into a position covering, touching or forming part of a surface.
（2）on作为副词：值班、表示持续性、向前（移动）、穿在身上。例句：The book is perhaps best known for having predicted that attack on the United States by Japan and an air war between the two powers.书也许最好地被为有知道预知在二力量之间的日本和一个空气战争的美国上的那个攻击。
（3）on作为形容词：在进行、在发生、在活动。例句：down on its prey. Suddenly it was hit by an arrow. It fluttered slowly down to the earth, and blood was pouring from the wound.忽然它被一只箭射中，它摇摇晃晃慢慢落在地面，鲜血从伤口涌出。
