31. When I walk past the park, I saw some children play football.
A walk B saw C children D play

gt: Khi tôi đi bộ qua công viên, tôi thấy đám trẻ chơi bóng đá -> việc đi bộ đã xảy ra trong quá khứ -> thì quá khứ đơn
32. After John eaten dinner, he wrote several letters and went to bed.
A eaten B he wrote C letters D went

gt: Thì QKHT

Hành động ăn diễn ra trước thời điểm viết thư trong quá khứ.

eaten ⇒ had eaten
33. What did you do at 9 o'clock last night? I phoned you but nobody answered.
A did you do B last night C phoned D nobody

gt: at 9 o'clock last night là dấu hiệu thì QKTD

did you do ⇒ was you doing
34. When I arrived at the station, the train has already left.
A when B arrived C at D has already

gt: thì QKHT
35. Ann and Susan have known each other during they were at school.
A have known B each other C during D were
36. She has disappeared three days ago, and they are still looking for her now.
A has disappearedB andC are still D for her

gt: Dấu hiệu: three days ago => chọn thì quá khứ đơn: S + V.ed

has disappeared => disappeared

37. After Mrs. Wang had returned to her house from work, she was cooking dinner
A returned B to her house C from work D was cooking
38. It’s the first time I saw this film
A It's B time C saw D this film

gt: cấu trúc it is the first/second..time + mệnh đề chia thì HTHT

saw⇒ have seen
39. After he graduates from university, he joined the army.
A after B graduates C from D the army

40. Up to now, there had been no woman being chosen the US president.

A up to now B had been C no D being chosen

gt: up to now là dấu hiệu thì HTHT

had been ⇒ has been

1. When I walk past the park, I saw some children play football.->was walking
2. After John eaten dinner, he wrote several letters and went to bed. ->had eaten 
3. What did you do at 9 o'clock last night? I was phoning you but nobody answered -> were you doing 
4. When I arrived at the station, the train has already left.->had
5. Ann and Susan have known each other during they were at school. ->since