15. The bed which I slept on had no mattress  

16. why

17. the boy who won the race yesterday is very happy

18. mrs Marks whose farm the stream flows across, is unhappy about.........

19.  her father who she looked after for over 20 years, died last year

20. the picture, which she was looking at, was famous.

1. The professor whose course I am talking is excellent.

2. I saw a lot of people and houses that went to the market.

3. I recently went back to Paris, where I was born.......

4. Do you know the music which is being played on the radio?

5. You didn't tell us the reason for which we have to cut down our daily expenses.

6. She left on the day which was rainy.