单词音标
英语音标：[ɒn]
美语音标：[ɑːn]

翻译
prep.在 ... 之上；由 ... 支撑着；在（某一天）；关于；基于

adv.穿着；向前（移动)；表示持续性

adj.表示已连接、处于工作状态或使用中；发生；值班

例句

They made their own judgment on his report.

他们凭他的报告作出自己的判断。

Why hasn't she got her glasses on?
她怎么没戴眼镜呢？

I got to know David on the second day of middle school. 

我在上中学的第二天就认识了大卫。

I didn't know what he was on about. It didn't make sense.

我不知道他说的什么。他说的没什么意义。