1. Last year we went to the farm   which my father once worked.

2. In front of my house, there is a tree,    which some birds are singing.

3. He’s the model    whom we should learn.

4. The problem    which you argued just now has been solved.

5. Is this the car     which you paid much money?

6. In the dark street, there wasn’t a single person   whom she could turn for help.

7. The factory   which I work is far from my hometown.