Exercise : Chia dạng đúng của động từ trong ngoặc ở thì quá khứ đơn và quá khứ tiếp diễn.
1. WhenI (arrive) at this house, he still(sleep)
2. Thelight (go)...........out whilewe(have)...............dinner.
3. Bill(have)...........breakfast whenI (stop)...........at this house thismorning.
4. WhenI (come)..............to his house, he (work)
5. Aswe(cross)............the street,we(see)..............an accident.
6. Tom (see)................a serious accident whilehe(stand)..................at the busstop.
7. Thechildren (play).................football when theirmother (come)................backhome.
8. Thebell (ring)............whileTom(take)..................a bath.
9. He(sit)..................in a car whenI(see).................him.
10. We(clean)...............the house whenshe(come)..............yesterday.