2.(happening or definitely going to happen)正在发生的
Is the meeting still on?会还在开吗？
There's a match on this weekend.这周末有一场比赛。
3.(be performing)正在表演的
I'm on in five minutes.五分钟后该我上场表演了。
4.to be on【板】(bowling)投球
5.【板】(relating to the leg side)(板球场)身后区的
the on side身后区
an on drive斜后方击球