The boy is on the school football team,为什么用介词on?

on 英音：[ɔn] 美音：[ɑn]
on
介词 prep.这是on本有的意思,看第十条.
10.属于...,参加...,是...的成员
He is on the school volleyball team.
他是校排球队队员.
1.在...上
He laid a hand on my shoulder.
他把一只手放在我肩上.
2.以...支持,挂在...上;以...为轴
There is a picture on the wall.
墙上有一幅画.
3.朝,向
4.靠近,在...旁,沿着
She stood on my left.
她站在我左边.
5.在...的时候,在...后立即
He jumped with joy on hearing the news.
他一听到这个消息就高兴得跳了起来.
6.关于,有关
The teacher made comments on our compositions.
老师就我们的作文作了讲评.
7.以...方式,通过
Did you hear it on the radio?
你是从收音机听到这消息的吗?
8.凭...,靠...;使用...,吃...
They said they were acting on instructions.
他们说他们是奉命行事.
9.处于...状态,进行中
10.属于...,参加...,是...的成员
He is on the school volleyball team.
他是校排球队队员.
11.加之于,重叠于
12.由...支付
Have another coffee on me.
再来一杯咖啡,我请客.
13.带在...身上
副词 ad.
1.继续
They talked on until midnight.
他们一直谈到深夜.
2.向前
3.穿上,盖上,连接上
It's cold today.Why don't you put your overcoat on?
今天很冷.为什么不把大衣穿上?
4.(机器)处于工作状态;开着;通着
He left the engine on while waiting for Joe.
他在等候乔时让汽车引擎开着.
5.上演着;在进行中
形容词 a.[Z]
1.(机器等)工作着的,开着的
2.正在上演的,在放映的
What's on for tonight at the cinema?
今晚电影院上映什么片子?
3.在发生的,在进行的
The strike is still on.
现在仍在罢工.
4.菜单上有的,供应的
I'd like to have some salmon if it is on.
如果有大马哈鱼供应,我想来一点.
5.【俚】知情的
6.【美】【俚】醉了的