1、表示原因。例句：
I didn’t hear what you said;I was looking at the picture.
我沒(méi)有聽見你的話，我在看那幅畫。
I haven’t finished my homework yet,I was helping my mother in the kitchen all day yesterday.
我還沒(méi)完成作業(yè)，我昨天一整天都在幫媽媽干廚房活。

2、對(duì)所說(shuō)的話進(jìn)行強(qiáng)調(diào)。在小說(shuō)的對(duì)話中，有時(shí)引述動(dòng)詞不用一般過(guò)去時(shí)，而用過(guò)去進(jìn)行時(shí)，意在強(qiáng)調(diào)所說(shuō)的話，語(yǔ)氣較重，且更為生動(dòng)。例句：
A：“Did they catch her?”Mary was asking.
“他們抓住她了嗎？”只聽得瑪麗問(wèn)道。
B:”No,she escaped.”Tom told her.
“沒(méi)有，她逃走了。”湯姆告訴她。

3、過(guò)去進(jìn)行時(shí)還可和when結(jié)構(gòu)遙相呼應(yīng)，含有意外之意。例句：
I was walking in the street when someone called me.
我正在街上走時(shí)突然有人喊我。

4、表示與現(xiàn)在事實(shí)相反或?qū)?lái)的猜想情況，有時(shí)表示不耐煩等情緒。例句：
I was going to phone you,but I just didn’t have time.
我本想給你打電話的，但就是沒(méi)有時(shí)間。
The basketball match was taking place the next day,but it had to be canceled because of the heavy rain.
籃球賽原定第二天舉行的，但因大雨不得不取消。
I thought you were never coming.
我以為你總不會(huì)來(lái)了。

5、用來(lái)陳述原因或用作借口。
She went to the doctor yesterday. She was having a lot of trouble with her heart.
她昨天去看病了。她患了很嚴(yán)重的心臟病。

6、與always,constantly等詞連用，表示感情色彩。例句:
The girl was always changing her mind.
這女孩老是改變主意。

7、表示動(dòng)作的未完成性。過(guò)去進(jìn)行時(shí)可以表示動(dòng)作的未完成性，即對(duì)某事了解的不全面，希望得到更詳細(xì)的情況。例句：
I was hearing Susan had entered the college.
我聽說(shuō)蘇珊上了大學(xué)。

8、表示繼續(xù)剛剛中斷的談話，用于日常生活中。例句：
As I were telling you,the boy took his stubbornness from his father.
正想我剛剛告訴你的，這孩子的犟脾氣是他爸爸遺傳給他的。
As she was telling me,we must depend upon ourselves to make our own way as best we can.
正如她所告訴我的，我們必須依靠自己竭盡全力走自己的路。

9、表示婉轉(zhuǎn)語(yǔ)氣，只限于want,hope,wonder等動(dòng)詞，用以提出請(qǐng)求。例句：
I was wondering if you could help me.
我想知道你是否能夠幫助我。
I was hoping you could send me the book.
我想知道你是否能把書借給我。

10、表示對(duì)比。
例句： He was not sitting idle,he was making preparations.
他沒(méi)有閑坐著，他在做準(zhǔn)備。
While the children were playing in the shade,their parents were working in the scorching sun.
孩子們?cè)跇涫a下玩耍，而他們的父母卻在烈日下勞作。
?