去的另一动作同时发生
I was having supper at 7:00 yesterday evening.
昨天晚上7点我正在吃晚饭。
She was playing the piano while I was reading the newspaper.
她弹钢琴时我在看报。
提示：
当句子意思很清楚时，我们也可以把两个动词都换成一般过去时。
We listened closely while the teacher read the text.
老师读课文时，我们都仔细地听着。
b.表示过去一段时间内正在进行的动作
We were talking about you the whole morning.
我们整个上午都在说你。
He was watching TV at home from 3:00 to 5:00 yesterday afternoon.
昨天下午从3点到5点他一直在看电视。
c. 表示按计划、安排过去将要发生的事
He told me that he was going soon.
他告诉我他很快就要走了。
She said she was leaving for New York the next month.
她说她下个月动身去纽约。
②过去进行时的特殊用法
a.表示故事发生的背景
It was snowing as the medical team made its way to the front.
那支医疗小组往前线行进时天正下着雪。
Tom slipped into the house when no one was looking.
汤姆乘没人注意时溜进了房间。
b.表示一个新的动作刚刚开始
过去进行时可用来引出一个新的动作，这种用法颇有点儿像镜头转换。
Five minutes later, he was standing at the door, smoking.
5分钟后，他已站在门口抽着烟。
The baby was crying hard, and suddenly the crying stopped.
这婴儿在大声啼哭，突然，哭声停止了。
c. 用来陈述原因或用作借口
She went to the doctor yesterday. She was having a lot of trouble with her heart.
她昨天去看病了。她患了很严重的心脏病。
I haven't finished my homework because I was helping my mother at home all day yesterday.
我作业没做完是因为我昨天一直帮妈妈在家干活。
d. 与always, constantly等词连用，表示感情色彩
The girl was always changing her mind.
这女孩老是改变主意。
In the past he was constantly asking me for money.
过去他总是向我要钱。
3．过去进行时与一般过去时的区别
①一般过去时往往表示某一动作已经完成，而过去进行时却表示动作在持续或未完成。
She wrote a letter to her friend last night.
她昨晚给朋友写了封信。（信写完了）
She was writing a letter to her friend last night.
她昨晚一直在给朋友写信。（信不一定写完）
②一般过去时表示只做一次动作，而过去进行时却表示动作反复地进行。
She waved to me.
她朝我挥了挥手。
She was waving to me.
她不断地朝
我挥手。
The boy jumped up and down.
这男孩跳了一下。
The boy was jumping up and down.
这男孩不停地跳着。
C.将来进行时
1．将来进行时的构成
将来进行时是由“shall/will + be +现在分词”构成的