後

後

"後" (hòu): behind, after, or later.

In this sentence, '後' emphasizes a period of time indicating the context of waiting.

我已經等了半個小時候。

I have already been waiting for half an hour.

Here, '之後' indicates a sequence in time, referring to the aftermath of an event.

事情發生之後，我才明白他的意思。

After the event happened, I understood his meaning.

In this context, '後面' indicates a spatial relation denoting the rear or behind.

請站到我的後面。

Please stand behind me.