1.was reading.....was watching (do cấu trúc while+QK tiếp diễn)

2.came....switched....checked (thì quá khứ)

3.sneaked....stole....left (thì quá khứ)

4.listened...was explaining (thì quá khứ đơn+ cấu trúc while)

5.were doing....were lying ( cấu trúc while)

6.woke...asked (thì quá khứu đơn)

1. While Tom (read) was reading , Amely (watch) was watching a documentary on TV.
2. Marvin (come) came home, (switch) switched on the computer and (check) checked his emails.
3. The thief (sneak) sneaked into the house, (steal) stole the jewels and (leave) left without a trace.
4. Nobody (listen) was listening while the teacher (explain) was explaining the tenses.
5. While we (do) were doing a sight-seeing tour, our friends (lie) were lied on the beach.
6. He (wake) woke up and (look) looked at his watch.

Qúa khứ đơn 

      tobe: S + was/ were + O

       động từ thường:S + V-ed/ V_{QK (bất quy tắc)} + O