不明飞行物到达时你在做什么？。What were you doing when the UFO arrived?,
在 的前面（外部） in front of,
在 的前面（内部）in the front of,
在图书馆in the library,
出 之外，摆脱get out of,
进入get into,
睡懒觉 sleep late,
睡得好 sleep well,
睡着get to sleep,
fall asleep,
沿 走walk down,
walk along,
(飞机)起飞；脱下（衣帽）take off ,
在星期日晚上on Sunday evening,
注意:（特指某日如星期、假日、某月某日或某个特定的上、下午、晚上用on）
在树上 in the tree,
在树上on the tree,
照相take photos,
在火车站at the train station,
跑开，逃跑run away,
as,+形容词原形 as,和 一样
她没有她姐姐漂亮。 She is not as beautiful as her sister,
我能跑得和他一样快。I can run as fast as he, I can run as fast as him,
为某人买东西buy something for somebody ,
为某人画东西draw something for somebody ,
为某人制作东西make something for somebody ,
走回家walk home,
在历史上in history,
例如for example,
在 城市in the city of,
在操场上on the playground,
十分钟前ten minutes ago,
发生（强调必然性）take place,
某事发生（强调偶然性）happen to something,
某人发生了某事（强调偶然性）happen to somebody,
你发生了什么事？ What has happened to you?,
你怎么了？What's the matter with you?,
What's wrong with you?,
当然of course,
sure,
certainly,
遍及全世界all over the world,
around the world,
在车站外outside the station,
在车站内inside the station,
相邻，紧贴next to,
接近于；在附近close to,
生病住院be ill in hospital,
生病在床be ill in bed,
听说（间接听到）hear about,
hear of,
沉默不语in silence,
保持沉默keep silent,
一次不寻常的经历an unusual experience,
干某事有乐趣 have fun doing something,
干某事有困难have a difficult time doing something,
日子不好过，困难时期 have a difficult time,
对 有意义have meaning to,
成为中国第一个太空宇航员become the first Chinese astronaut in space,
一个民族英雄a national hero,
全世界出名be famous all over the world,
第一次 for the first time,
我到的时候你在干什么？。 What were you doing when I arrived?,
当时你在干什么？。 What were you doing at that time?,
昨晚八点你在干什么？。What were you doing at eight last night?,
昨天从九点到十点你在干什么？。What were you doing from nine to ten yesterday?,
我在做某事。I was doing something ,
When+一般过去时的时间状语从句
怎么样How about,
What about?,
当有人在做某事时，我也在做某事。While somebody was doing something , I was doing something,
当不明飞行物着陆时，你正在干啥？What were you doing when the UFO landed?
当妈妈正在做饭时，我在看电视。While my mother was cooking ,I was watching TV,
我在街上走的时候，一个不明飞行物正好落在我面前。I was walking down the street when a UFO landed right in front of me,
你可以想象这是多么奇怪。You can image how strange it was,
我跟着去看它要去哪里。I followed to see where it was going,
太棒了！ Isn't that amazing!,
她没有想到往车站外面看。She didn't thinking about looking outside the station,
今天早上我太累了。很难下床I was so tired this morning, It was difficult to get out of the bed,
刘翔在2004年奥运会上获得金牌。Liu Xiang won the gold medal at the two thousand four Olympics,
北京被选为2008年奥运会的东道主。Beijng was made host to the two thousand and eight Olympics,
当人们听到历史上重大事件的消息时，他们常常记得自己在做什么。People often remember what they were doing when they heard the news of important events in history,
这是美国现代史上最重要的事件之一。This was one of the most important events in modern American history,
即使是最日常的活动似乎也很重要。Even the most everyday activities can seem important,
我们的老师让我们停下正在做的事情来听。Our teacher asked us to stop what we were doing and listen,
然而，在最近的时代，大多数美国人还记得当纽约世贸中心被恐怖分子摧毁时他们在做什么。However, in more recent times, most Americans remember what they were doing when the World Trade Center in New York was destroyed by terrorists,
当然，并非所有的历史事件都像这样可怕。Not all events in history are as terrible as this, of course,
他绕地球飞行了大约22个小时。 His flight around the Earth lasted about 22 hours,
（昨天傍晚八点半她正在做家庭作业。）She was doing her homework at half past eight yesterday evening,
（那个时候我们正在吃晚饭。）We were having supper at that time,
在单句中使用过去进行时来表达时必须把该动作正在进行中的时间表明清楚，否则就不合逻辑了。I was taking a bath yesterday, 这句错误，昨天我正在洗澡？昨天24小时都正在洗澡吗？逻辑错误。
（昨天我洗了澡。）I took a bath yesterday,
如果由上下文的文意，或者对交谈中的话意可以了解“动作正在进行中的时间”，单句里就使用过去进行时来表达是很普通的
我昨天晚上给你打了电话。I called you up yesterday evening,
是吗？什么时候？。Did you? At what time?,
（大约在十点钟。）At around ten o'clock,
（哦，当时我正在洗澡。）Oh, I was taking a bath then,
过去有二动作A和B，在B动作发生时稍早发生的A动作正好在进行中，这种表达法通常都是复句（主句+副词从句）。
今天早上我起床时妈妈正在厨房里准备早餐。When I got up this morning, Mother was preparing breakfast in the kitchen,
修饰过去进行时的时间副词：过去的某一定点时刻（at, + 过去的时刻），then, （,at that time,）（那时，当时），all, + 时间，“When, 或者While, 或者As, ”。