III. Cho dạng đúng của động từ trong ngoặc ở thì quá khứ tiếp diễn.
1. At this time last year, they (build) this house.
2. I (drive) my car very fast when you called me.
3. I (chat) with my friends while my teacher (teach) the lesson yesterday.
4. My father (watch) TV when I got home.
5. At this time yesterday, I (prepare) for my son's birthday party.