1 Mai's sister didn't love him. He wanted to marry her.
-> Mai's sister didn't love the boy who wanted to marry her.
* Who dùng để thay thế chủ ngữ chỉ người.
2 I don't like HCM city. It is very noisy.
-> I don't like HCM city which is very noisy.
* Which dùng để thay thế vật đóng vai trò là chủ ngữ hoặc túc từ.