1．John_______（work） all day yesterday.
2．He _______（walk） home when the （rain）_______begin.
3．What______you _______（do） at ten o'clock yesterday？
    I_______（study） in class．
4．When Harry _______（have） breakfast Lily _______（telephone） him．
5．When I ________ （go） to school this morning I ______ （see） a car running into
    a bus．
6. This time yesterday Jack ______ (mend) his bike.
7. I ______ (write) a letter at ten last night.
8. It was six. The Greens ______ (have) supper.
9. When you ______ (knock) at the door yesterday,I ______ (do) some washing.
10.While my mother ______ (watch) TV, I ______(make) a kite.
11.While we__________(wait)for the bus,a girl__________(run)up to us.
12.I__________(telephone)a friend when Bob__________(come)in.
13.Jim__________(jump)on the bus as it__________(move)away.
14.We__________(test)the new machine when the electricity__________(go)off.
15.She______(not want)to stay in bed while the others________(all,work)in the fields.
16.While mother________(put)Cathy to bed,the door bell________(ring).

答案： working 2.He was walking home when the rain began. 3. were you doing was studying 4. was having telephoned 5. was going saw 6. was mending 7. was writing 8. were having 9. knocked was doing 10. was watching was making waiting;ran telephoning;came ;was moving testing;went want;were all working putting;rang