经理：
Did you serve this gentleman half an hour ago,Amy?He says he's the man who bought these books.艾米,半小时前你接待过这位先生吗?他说他就是买这两本书的人.
艾米：I can't remember.The man who i served was wearing a hat.
我记不起来了,我接待的那个人戴着一顶帽子.
研究的是这句The man who i served was wearing a hat.
1 这句是什么句型?
2 wearing 为什么不用 wore 或 worn
3 用 who