6点30分用英语表达是：half past six；

half：n. 一半; 半; (比赛、音乐会等的)半场，半局; (啤酒等饮料的)半品脱。

past：adj. 过去的; 昔日的; 刚过去的; 刚结束的; 从前的; 以往的。

He arrived at about half past six.

他大约六点半左右到。

It's half past six.

现在是六点半。

It was half past six;

那时正是六点半；

The post office closes at half past six.

邮局六点半关门。

We waited till half past six for you.

我们等你等到六点半。