Ta có:

who: chỉ người(đóng vai trò làm chủ ngữ)

which: đồ vật

that: dùng trong câu có cả sự vật và con người

whom: chỉ người nhưng chỉ đóng  vai trò làm vị ngữ

whose: chỉ quyền sỡ hữu

_____________________________

2 I was talking to a man. He is a colleague of mine

`->`A man whom I was talking about is a colleage of mine

`->` I didn't understand what you said(không cần relative pronouns)

4 She looks ill. It's a bit worrying.

`->` She looks ill that has a bit worrying

. 5 He's a famous politician. His wife left him last week.

`->` He's the famous politician who his wife left him last week

6 This house was built in 1534. It one of the oldest houses in the village.

`->` This house which was built in 1534 is one of the oldest houses in the village.

$#FromTha$

5.He's a famous politician. His wife left him last week.

   He is a policeman who was left by his wife last week.