用定语从句翻译下列句子 在线等 急！！！

1.This is the factory which I visited a few days ago.
2. I want to tell you some thing which I have heard of .
3.We like the football match which was held last week.
4.This is the old man who got lost,
5 .The boy which you are talking about is one of my good friend.

1. This is the factory which I visited a few days ago.
2. I want to tell you what I've heard of.
3. We like the football match which was held last week.
4. This is the old man who has lost his way.
5. The boy whom you are talking about is one of my good friends.