(1) 过去进行时强调动作在过去某时刻正在进行或持续，而一般过去时表示动作的完成。如：He was writing his composition last night. 他昨晚在写作文。(不一定写完)
He wrote his composition last night. 他昨晚写了一篇作文。(已经写完)
(2) 表示过去的状态、感觉及心理活动的静态动词(如be, like, love, hate, fear, own, hear, see, know, want, notice)可用于一般过去时，但通常不用于进行时。如：
I hated it when a man spoke with his mouth full of food. 我讨厌人们说话时口里含着食物。
(3) 一般过去时与always, constantly, forever, continually等连用，表示过去经常性、习惯性的动作而过去进行时与always, constantly, forever, continually等连用，表示动作的重复，常带有感****彩。如：
He always got up at six. 他过去总是六点起床。
He was always thinking of his work. 他总是一心想到工作。
(4) 有时过去进行时可以用来替换一般过去时，但一般过去时表示主语的行为是经过认真考虑的;而过去进行时表示一种较随便或没有进行仔细考虑的行为。如：
I thought that he would agree with us. 我原以为它会同意我们的。
I was thinking of persuading him to follow my advice. 我想到了要说服他接受我们的建议。