Ответ:

1 He showed us the street where he was born.

2 Can you describe the man who stole your wallet?

3 Celia is wearing the dress which i wanted to buy!

4 Our hotel room has a balcony where you can sit and look at the sea.

5 A friend is a person who always helps you.

6 Is that the restaurant where we had that wonderful pizza?

7 i've lost the book which Paul lent me!