1.表示過(guò)去某一時(shí)刻或階段正在發(fā)生的動(dòng)作。. I was playing chess at 8 yesterday evening.
    . When I arrived, they were watching TV.
    . They were doing housework this time last week.
    2.用于條件狀語(yǔ)從句中表示過(guò)去將來(lái)進(jìn)行的動(dòng)作。. She told me to wake him up if she was sleeping.
    . I asked my friend to warn me about it as long as I was driving too fast.
    3.過(guò)去某時(shí)將發(fā)生的事。可參考—2(4). They told me that they were leaving for New York.
    . He was going out when I arrived.
    練習(xí)題：
    1. My brother ________ while he ________ his bicycle and hurt himself.
    A. fell / was riding B. feel / were riding
    C. had fallen / rode D. had fallen / was riding
    2. He ________ his leg as he ________ in a football match.
    A. broke / played B. was breaking / was playing
    C. broke / was playing D. was breaking / played
    3. -Myfather will be here tomorrow. -I thought that he ________ today.
    A. was corning B. is coming
    C. will come D. comes
    4. Jack was going out of the shop when he collided with an old woman who ________ in.
    A. come B. was coming C. had been coming D. had come
    5. Michike couldn't come to the telephone when Mr. Smith called her because she ________ in the lab.
    A. had been working B. has been working
    C. was working D. worked
    練習(xí)答案： 1. A 2. C 3. A 4. B 5. C