11. The boy who I made fun of him is my cousin.

12. The student who sits next to me is from China.

13. I thanked the woman who had helped me.

14. The professor whose course I am taking is excellent.

15. Mr. Smith, who I had come to see, said he was too busy to speak to me.

16. I saw a lot of people and horses that went to market.

11. The boy is my cousin. You make fun of him.

-> The boy whom you make fun of is my cousin.
12. The student is from china. He sits next to me.

-> The student who sits next to me is from china.
13. I thanked the woman. This woman had helped me.

-> I thanked the woman who had helped me.
14. The professor is excellent. I am taking his course.

-> The professor whom I am taking course is excellent. 
15. Mr. Smith said he was too busy to speak to me. I had come to see him.

-> Mr. Smith whom I had come to see said was too busy to speak to me.
16. I saw a lot of people and horses. They went to market.

-> I saw a lot of people and horses who went to market.