选择who, that, where 填空。
1. This is the house _______ we built last year.
2. This is the house _______ we lived ten years ago.
3. I can't find a house _______ is suitable for us to live.
4. He is the man _______ can help you.
5. Is there a zoo _______ we can see tigers around here?
6. I like musicians ______ write their own songs.
