1. The police officer who gave me directions was friendly. 

2. The building which was destroyed in the fire has now been rebuilt.

3. I like the shirt which you wore to class yesterday.

4. A bomb which went off this morning caused a lot of damage.

- Mệnh đề quan hệ chỉ người: who.

- Mệnh đề quan hệ chỉ vật: which.

@ Mimzyy2509:3

1. the police officer was friendly. he gave me directions

→The police officer giving me directions was friendly 

2. the building has now been rebuilt. it was destroyed in the fire

→ The building which was destroyed in the fire has now been rebuilt.

3. I like the shirt. you wore it to class yesterday

→ I like the shirt whom you wore to class yesterday. 

4. A bomb caused a lot of damage. It went off this morning

→The bomb which went off this morning caused a lot damages.

# Chúc bn hok tốt!!!~