过去进行时，以及while的用法

表示过去某时正在发生的动作。如:
We were having dinner when they came. 他们来的时候,我们正在吃饭。
I was reading a newspaper at nine o'clock yesterday evening. 昨晚九点我在看报纸。
What were you doing last summer? 去年夏天你干什么来着?
He was talking all the time. 他一刻不停地在讲话。

while表示“在某一段时间里”或“在......期间”,其所引出的从句的动作是延续性的,并侧重表示和主句的动作同时发生。如:
While you were away, two persons came to see you. 你不在时有两个人来找你。
While the teacher paraphrased the text in English, the students listened attentively and took notes. 当老师用英语阐释课文时,同学们注意地听并且做着笔记。
while还可用作并列连词,相当于whereas, 连接一个表示对比的并列分句。如:
Mary was dressed in blue while Jane was dressed in red. 玛丽穿蓝色衣服,而珍妮穿红色衣服。

1 (a) during the time that; when 在...期间; 当...的时候: He fell asleep while (he was)
doing his homework. 他做著做著功课就睡著了. * While I was in Madrid there was a carnival.
我在马德里的时候正赶上狂欢节. * While (locked up) in prison, she wrote her first novel.
她在狱中写出了第一部小说. (b) at the same time as 与...同时: While Mary was writing a letter,
the children were playing outside. 玛丽写信时孩子都在外面玩儿. * He listens to the radio
while driving to work. 他去上班一边开著车一边听音乐. * I lived in a hostel while I was a
student. 我求学期间住在青年招待所里.
2 (used to show a contrast 用以表示对比或相反的情况): I drink black
coffee while he prefers it with cream. 我爱喝清咖啡而他喜欢加奶油的. * English is understood
all over the world while Turkish is spoken by only a few people outside Turkey
itself. 英语世界通行, 但土耳其语离开本国就很少有人说了.
3 (fml 文) although 虽然: While I admit that
there are problems, I don't agree that they cannot be solved. 尽管我承认有问题存在,
但我不同意说这些问题不能解决.