1. Hang on a moment.

稍等。

2. Give me a second.

请等一下。

3. I'll be right with you.

我马上就来。

4. Half a moment.

马上。

5. I'm in the middle of something. Could you call back later?

我现在很忙，你能过会给我打电话吗?

6. I can't right now, but maybe later.

我现在办不了，可能过几天吧。

7. Sorry, I'm a bit tied up right now.

不好意思，我现在有点忙不过来了。