Who - Làm chủ ngữ, chỉ người
Which - Làm chủ ngữ hoặc tân ngữ, chỉ đồ vật, động vật
Whose - Chỉ sở hữu cho người và vật
Whom- Làm tân ngữ, chỉ người
•Do you know the girl who is standing outside the school?
• The man who lives next-door is Chinese.
• The dictionary which you gave her is very good.
• A burglar is someone who breaks into a house and steals things.
• The family whose car was stolen last week is the Bills.
• A bus is a big car which carries lots of people.
• The man whose mobile was ringing did not know what to do.
• Buses which go to the airport run every half hour.