用适当的关系代词填空。
1. This is the comrade _____ will go to the south with us tomorrow.
2. Who's the student _____ the teacher is talking with?
3. I like the present _____ you've sent to me.
4. The nurse _____ we talked about can speak English well.
5. This is the most difficult job _____ we've ever done.
6. This is the cleverest man _____ I've ever known.
7. I bought all _____ was necessary.
8. The old gentleman _____ you met just now is a famous writer.
9. The girl to _____ I lent my bike works in a hospital.
10. All _____ come are welcome.
11. This is the girl _____ songs you heard last night.
12. She was the brave girl _____ name is known to everybody here.
13. Thank you for the help _____ you've done for me.
14. This radio set _____ we have had for two years is a good one.
15. The next question _____ I found difficult to answer was put to me by Mary.