?在復(fù)合句中，如果主要動作和背景動作都是延續(xù)的或同時(shí)發(fā)生的，那么主從句的動詞都可用過去進(jìn)行時(shí)。
例如： While he was waiting for the bus, he was reading a newspaper.他邊等車邊看報(bào)。 (兩個(gè)動作都是延續(xù)的)
? ? ? ? ? He was cleaning his car while I was cooking. 他擦車時(shí)我在做飯。(兩個(gè)動作同時(shí)進(jìn)行)
?通常不能用于過去進(jìn)行時(shí)的動詞主要有：
? ? ? ?agree, is,am,are, believe, belong, care, forget, hate, have(擁有), hear, know, like, love, mean, mind, notice, own, remember, seem, suppose, understand, want, wish等。
例如：誤：I was knowing the answer.
? ? ? ? 正：I knew the answer. 我知道答案。
　　 ? 誤：I wasn‘t understanding him.
? ? ? ? 正：I didn‘t understand him. 我不明白他的意思。