常用的時間狀語
　　this morning, the whole morning, all day yesterday, from nine to ten last evening, when, while
　　My brother fell while he was riding his bicycle and hurt himself.
　　It was raining when they left the station.
　　When I got to the top of the mountain, the sun was shining.
典型例題
　　(1) Mary _C_ a dress when she cut her finger.
　　A. made B. is making C. was making D. makes
　　答案C. 割傷手指是已發(fā)生的事情，應(yīng)用過去時。同 時，when表時間的同時性，"瑪麗在做衣服時"提供事情發(fā)生的背景，因此用過去進行時。
　　(2) As she _b__ the newspaper, Granny ___ asleep.
　　; was falling B. was reading; fell C. was reading; was falling D. read;fell
　　答案B. 句中的as = when, while，意為"當(dāng)……之時"。描述一件事發(fā)生的背景時，用過去進行;一個長動作發(fā)生的時候，另一個短動作發(fā)生。句意為 "在她看報紙時，奶奶睡著了。"句中的 fell (fall的過去時)，是系動詞，后跟形容詞，如：fall sick。
過去進行時的基本用法:表示過去某個時刻或時間正在進行過持續(xù)進行的動作,句中往往需要有時間狀語來表示這一特定的時間.
What were they doing just now? 他們剛才在干什么?