Present - Past - Present perfect - Past perfect Chúng ta dùng Present perfect khi ta nghĩ một tình huống chưa kết thúc, và Past simple khi ta nghĩ rằng nó đã kết thúc: 1. I have lived in Hanoi for a year. She has known him since school. Has Peter been ill? 2. I lived in Hanoi for a year. She knew him in school. Was Peter ill? Present perfect với cụm từ diễn tả khoảng thời gian cho đến hiện tại (lately, so far). Past simple với cụm từ chỉ khoảng thời gian đã kết thúc sớm hơn (last night, yesterday): 3. Have you seen any good film lately? So far the new teacher hasn't given us any homework. 4. Did you see that film last night? I didn't do the homework yesterday. Trong mệnh đề bắt đầu với after, as soon as, và when, chúng ta có thể dùng Present perfect cho hành động đã hoàn thành trong tương lai, và Past simple cho hành động đã hoàn thành trong quá khứ: 5. After/As soon as/When he has made his copies, I will do mine. (= He hasn't made his copies yet. Neither have I.) 6. As soon as he made his copies, I did mine. (= He made his copies first, then I made mine.) 7. When he arrived in the morning, we had started work. (= We started work before he arrived) 8. When he arrived in the morning, we started work. (= We started work after he arrived) Trong câu điều kiện, chúng ta dùng Past perfect cho việc đã chẳng xảy ra, và Past simple cho việc có thể xảy ra: 9. If you had come, you could have stayed with us. If I'd known, I certeinly would have helped. 10. If you came, you could stay with us. If I saw anyone doing that, I certainly would try to stop it. Chúng ta thường dùng Past perfect, không dùng Past simple, với vài trạng từ (already, just, still): 11. The ambulance came quickly, but the crash victim had already died. 12. The books still hasn't arrived when I left. 13. The students had just opened their books when the fire alarm went off. Khi chúng ta đang nói về một việc trong quá khứ với thì Past simple (won), và muốn đề cập đến việc xa hơn nữa trong quá khứ, ta dùng Past perfect (had won): 14. Jenny won her first gold medal in 2004. She had won two silver medals in previous Olympics, but this was het first gold.