3:30用英文怎么说

3:30用英语可以说成 "three thirty" 或 "half past three"。

"Three thirty" 来源于数字 "3" 和 "30" 的发音。

"Half past three" 来源于将一个小时分成两半，"half past" 表示过了一半。

例句：

I'll meet you at three thirty. (我会在3:30和你会面。)
The meeting is scheduled for half past three. (会议安排在3:30。)