過去進(jìn)行時(shí)的主要用法
1.表示過去某一時(shí)間內(nèi)（正在）進(jìn)行的動(dòng)作
如：I was doing my homework at 9 p.m.last Sunday.
2.表示一動(dòng)作正在進(jìn)行時(shí),另一動(dòng)作同時(shí)正在進(jìn)行.
(1)用while連接（while只接doing）（注：如果主句和從句都是一般過去時(shí),可以用while連接兩個(gè)句子）
例:My mother was cooking while I was doing my homework.(可以持續(xù)動(dòng)作時(shí)態(tài)一致)
(2）when表示（when可以接doing或did,when后動(dòng)作時(shí)間長(zhǎng),用doing,時(shí)間短,用did）
例:I was doing my homework when my mother came in.(間接表達(dá)了具體時(shí)間)
3.重復(fù)的動(dòng)作
When he worked here,John was always making mistakes.
4.表示過去將要發(fā)生的動(dòng)作
She told us Mr.Lee was arriving here.
5.用于故事,以提供其時(shí)間背景
6.表示禮貌
7有時(shí)可強(qiáng)調(diào)過去某一動(dòng)作延續(xù)時(shí)間較長(zhǎng)