在过去进行时中,什么时侯,主语和从句都用过去进行时,（由while或 when引导时）

在过去进行时中,什么时侯,主语和从句都用过去进行时,（由while或 when引导时）
老师说,when后面用一般过去式,while后面用过去进行时.可为什么,我在做题中,看到主语和从句都用过去进行时,而且中间是while引导的从句,我不懂!什么时候主语和从句都用过去进行时啊?

首先,when 跟 while的用法我们一起来复习一遍：

when, while这两个词都有"当……时候"之意,但用法有所不同,使用时要特别注意. ①when意为"在……时刻或时期",它可兼指"时间点"与"时间段",所引导的从句的动词既可以是终止性动词,也可是持续性动词.如： When I got home, he was having supper.我到家时,他正在吃饭. When I was young, I liked dancing.我年轻时喜欢跳舞. ②while只指"时间段",不指"时间点",从句的动词只限于持续性动词.如： While I slept, a thief broke in.在我睡觉时,盗贼闯了进来. 辨析 ①when从句与主句动作先后发生时,不能与while互换.如： When he has finished his work, he takes a short rest.每当他做完工作后,总要稍稍休息一下.(when = after) When I got to the cinema, the film had already begun.当我到电影院时,电影已经开始了.(when=before) ②when从句动词为终止性动词时,不能由while替换.如： When he came yesterday, we were playing basketball.昨天他来时,我们正在打篮球. ③当从句的谓语是表动作的延续性动词时,when, while才有可能互相替代.如： While / When we were still laughing, the teacher came in.正当我们仍在大声嬉笑时,老师进来了. ④当从句的谓语动词是终止性动词,而且主句的谓语动词也是终止性动词时,when可和as通用,而且用as比用when在时间上更为紧凑,有"正当这时"的含义.如： He came just as (or when) I reached the door.我刚到门那儿,他就来了. ⑤从句的谓语动词如表示状态时,通常用while.如： We must strike while the iron is hot.我们应该趁热打铁. ⑥while和when都可以用作并列连词. Mike is tall while his brother is short.迈克的个子很高,然而他弟弟很矮. Mary was on her way home when two big boys stopped her.玛丽正走在回家的路上,这时两个大个子男孩拦住她. 过去进行时：一、 概念和用法：过去进行时表示在过去某一时刻或某一段时间内进行或发生的动作.其形式为was /were + V-ing.常与表示过去的时间状语连用,如：last night, last Saturday等；或者与when, while, as引导的过去时间状语连用.例如： We were watching TV from seven to nine last night. 昨天晚上七点到九点的时候我们在看电视. What was he researching all day last Sunday? 上周日他一整天都在研究什么?　　二、 过去进行时可以表示在过去某个时间点发生的事情.时间点可以用介词短语、副词或从句来表示.如： What was she doing at nine o‘clock yesterday? 昨天晚上九点她在做什么? (介词短语表示时间点) When I saw him he was decorating his room. 当我看见他的时候他正在装饰房间. (when从句表示时间点)　　三、 在复合句中,如果主要动作和背景动作都是延续的或同时发生的,那么主从句的动词都可用于过去进行时.例如： While he was waiting for the bus, he was reading a newspaper.他边等车边看报. (两个动作都是延续的) He was cleaning his car while I was cooking. 他擦车时我在做饭.(两个动作同时进行)　　四、 通常不能用于过去进行时的动词主要有：agree, is,am,are, believe, belong, care, forget, hate, have(拥有), hear, know, like, love, mean, mind, notice, own, remember, seem, suppose, understand, want, wish等.　　例如： 误：I was knowing the answer. 正：I knew the answer. 我知道答案.　　误：I wasn‘t understanding him. 正：I didn‘t understand him. 我不明白他的意思.　　[编辑本段]句型　　肯定句：主语+was/were+doing+其它　　否定句：主语+was/were+not+doing+其它　　一般疑问句及答语：Was/Were+主语+doing+其它 答语：Yes,I was./No,I wasn't.　　特殊疑问句：特殊疑问词+was/were+主语+doing+其它　　过去进行时vs一般过去时　　都强调过去发生的事　　进行时强调过程,不一定完成　　过去时强调事件,一定完成　　p,s表示一个动作正在进行时,另一个动作发生了　　如：He played when I was studying.