2. I thanked the woman who had helped me.

(Tôi cảm ơn người phụ nữ đã giúp đỡ tôi.)
3. The professor whose course I'm taking is excellent.

(Giáo sư mà khóa học tôi đang theo học rất xuất sắc.)
4. The man whose opinions I respect most is my father. 
5. She is the most intelligent woman that I have never met.
6. Do you know the music which is being played on the radio?
7. I recently went back to Paris which is still as beautiful as a pearl.
8. I recently went back to Paris where I was born nearly 50 years ago.
9. The day when she left was rainy.
10. The man whose name I don't remember is an artist.
11. That car whose engine is very good belongs to Dr.Clark.
12. Thank you very much for the present which you sent me.
13. This is Mrs.Jones whose son won the championship.
14. My mother who is over 45 still goes in for sports.

15. The young man whom you met at any place last night is my brother's friend.
16. Mr.Green, whose wife teaches singing, is very kind to everyone.
17. Tom's brother, who lives in London, is an engineer.
18. The cottage which you see at the foot of the fill is built of wood.
19. He intorduced me to his students, most of whom were from abroad.
20. Mary and Margaret, whom you met yesterday, were twins.

Giải thích:

1. WHO

- làm chủ từ trong mệnh đề quan hệ

- thay thế cho danh từ chỉ người

….. N (person) + WHO + V + O

2. WHOM

- làm túc từ cho động từ trong mệnh đề quan hệ

- thay thế cho danh từ chỉ người

…..N (person) + WHOM + S + V

3. WHICH

- làm chủ từ hoặc túc từ trong mệnh đề quan hệ

- thay thế cho danh từ chỉ vật

….N (thing) + WHICH + V + O

….N (thing) + WHICH + S + V

4. THAT

- có thể thay thế cho vị trí của who, whom, which trong mệnh đề quan hệ quan hệ xác định

* Các trường hợp thường dùng “that”:

- khi đi sau các hình thức so sánh nhất

- khi đi sau các từ: only, the first, the last

- khi danh từ đi trước bao gôm cả người và vật

- khi đi sau các đại từ bất định, đại từ phủ định, đại từ chỉ số lượng: no one, nobody, nothing, anyone, anything, anybody, someone, something, somebody, all, some, any, little, none.

* Các trường hợp không dùng that:

- trong mệnh đề quan hệ không xác định

- sau giới từ

5. WHOSE

Dùng để chỉ sở hữu cho danh từ chỉ người hoặc vật, thường thay cho các từ: her, his, their, hoặc hình thức ‘s

…..N (person, thing) + WHOSE + N + V ….

=>
2. I thanked the woman who had helped me.
3. The professor whose course I'm taking is excellent.
4. The man whose opinions I respect most is my father. 
5. She is the most intelligent woman that I have never met.
6. Do you know the music which is being played on the radio?
7. I recently went back to Paris which is still as beautiful as a pearl.
8. I recently went back to Paris where I was born nearly 50 years ago.
9. The day when she left was rainy.
10. The man whose name I don't remember is an artist.
11. That car whose engine is very good belongs to Dr.Clark.
12. Thank you very much for the present which you sent me.
13. This is Mrs.Jones whose son won the championship.
14. My mother who is over 45 still goes in for sports.

15. The young man whom you met at any place last night is my brother's friend.
16. Mr.Green, whose wife teaches singing, is very kind to everyone.
17. Tom's brother, who lives in London, is an engineer.
18. The cottage which you see at the foot of the fill is built of wood.
19. He intorduced me to his students, most of whom were from abroad.
20. Mary and Margaret, whom you met yesterday, were twins.