Công thức thì QKTD 

(+) S + was/were + Ving 

(-) S + was/were+ not + Ving 

(?) Was/Were +S +Ving? 

--> Diễn tả hành động đang xảy ra ở 1 thời điểm nào đó trong quá khứ 

--> Diễn tả hành động đang xảy ra thì có hành động khác chen vào (while / when)

DHNB: at + giờ + thời gian trong QK, at this time + thời gian trong QK, ...

Công thức thì QKĐ (V: thường)

(+) S + V2/ed 

(-) S + didn't + V1 

(?) Did + S+ V1?

DHNB: ago, last (year, month ...), yesterday, in + năm QK, ...

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1. When I saw her, she was washing the dishes.

2. They didn't want to watch TV.

3. She tried to open the door but she couldn't. 

4. John opened the door, looked out and began to run.

5. We were watching TV when he had an accident. 

6. He didn't believe me although I told the truth.

7. While I was sleeping, the bell rang.

8. I didn't want to go to the beach.

9. My brother was having a rest while my mother was cooking.

10. They were playing football when we saw them yesterday.

`color{orange}{~MiaMB~}`