Lưu ý:

Hầu hết các câu phía dưới đều áp dụng cách dùng phổ biến của thì QKTD là: "Thì QKTD diễn tả hành động đã đang xảy ra trong quá khứ thì một hành động khác xen vào/ xảy đến" (nên câu nào ko áp dụng cách dùng này c sẽ gthich rõ phía dưới nha)

1. The doorbell (ring)_____ while Tom (watch)_____ TV last night.

⇒ rang - was watching
2. How fast_____ you (drive)_____ when the accident (happen)_____?

⇒ were you driving - happened
3. Anna (make)_____ dinner when Martin (arrive)_____ home last Sunday.

⇒ was making - arrived
4. The light (go)_____ out while we (have)_____ dinner yesterday, but it (come)_____ on again after ten minutes.

⇒ went - were having - came
5. What_____ you (do)_____at this time yesterday?
- I (work)_____ on the computer.

⇒ were you doing - was working

DHNB thì QKTD "at this time yesterday"
6. It suddenly (begin)_____ to rain while Laura (sit)_____ in the garden.

⇒ began - was sitting
7. Sam (take)_____ a photograph of me while I (not look)_____.

⇒ took - wasn't looking
8. When I (see)_____ them, they (try)_____ to find a new house near their work.

⇒ saw - were trying
9. I (walk)_____ along the street when I suddenly (feel)_____ something hit me in the back. I (not know)_____ what it (be)_____.

⇒ was walking - felt - didn't know - was
10. Last night I (drop)_____ a plate when I (do)_____ the washing up. Fortunately it (not break)_____

⇒ dropped - was doing - didn't break