1. Last night I was reading when suddenly I heard a shout.

2. The postman came while I was having lunch.

3. When we went out, it was raining.

4. Were you watching TV when I phoned you?

5. We met Ann at the party yesterday, she was wearing a lovely white dress.

6. The boys broke the window while they were playing football.

7. I was home late, but my friends were waiting when I arrived.

8. He said that he wasn't driving fast when the accident happened.

9. Tom fell off the ladder while he was painting the ceiling.

10. What were you doing at this time yesterday?

Những chỗ điền was/were + V-ing là hành động đang diễn ra trong quá khứ, thì có một hành động khác xen vào điền V-ed (quá khứ đơn). Theo cấu trúc của thì QUÁ KHỨ TIẾP DIỄN

Giải thích:

9. Có while-> dấu hiệu của Quá khứ tiếp diễn

10. At this time yesterday-> dấu hiệu của Quá khứ tiếp diễn

1. Last night-> dấu hiệu của thì QKD mà có when-> chia thì QKTD

2. While -> chia thì QKTD

3. Có when 

4. Có when

5. Yesterday-> QKD

6. While 

7. When

8. Có when -> QKTD nhưng đây là câu gián tiếp -> lùi thì