Giúp mình 5 câu này nhé ( nhấn mạnh câu chẻ chủ ngữ )

1. It was the boy who visited his uncle last month. 

2. It was my mother who bought me a present on my birthday.

3. It was Huong and Sandra who sang together at the party.

4.  It was Nam’s father who got angry with him.

5. It was the boys who played football all day long.

it + dạng liên hợp của to be + X + mệnh đề phụ. trong đó nó là một đại từ khe hở và X thường là một cụm danh từ