IV. Each of the following sentences has one mistake. Identify and correct the mistakes. 16. While we were on holiday, we were spending most of our time sightseeing. 17. Paul listened to his iPod, so he didn't hear the doorbell ring. 18. He is a most intelligent student in our class. 19. Your new car is more cheaper than John's. 20. He left college when he is 17.

Cách làm:
- Đọc từng câu một và tìm lỗi sai trong câu đó.
- Sửa lỗi sai đó theo quy tắc ngữ pháp hoặc cách dùng từ đúng.

Câu trả lời cho câu hỏi:
16. While we were on holiday, we spent most of our time sightseeing.
17. Paul listened to his iPod, so he didn't hear the doorbell ring.
18. He is the most intelligent student in our class.
19. Your new car is cheaper than John's.
20. He left college when he was 17.

He left college when he was 17.

Your new car is cheaper than John's.

He is the most intelligent student in our class.

Paul listened to his iPod, so he didn't hear the doorbell ringing.