Unit 5 重点语法
( 1 ) 过去进行时的用法。
过去进行时表示过去某一时刻或某一段时间内正在进行或发生的动作，由“was / were + 现在分词”构成。
I/ He / She was woring.
We/ You/ They were woring.
I / He / It was not woring.
We / You / They were not woring.
Was I woring?
Yes, you were.
No, you were not.
Were you woring?
Yes, I was.
No, I wasn’t
Was he/ she/ it woring?
Yes, he/ she/ it was.
No, he/ she/ it wasn’t.
Were we/ you/ they woring? Yes, you/ we/ they were.
No, you/ we/ they weren’t.
表示过去进行时的时间状语有：at that time, this time yesterday, at ten yesterday evening, from eight to twelve yesterday 以及when, while引导的时间状语从句。
It was raining at 6 o’cloc this morning.
What were you doing this time last night?
He was sleeping when the UFO arrived.
( 2 ) 与一般过去时的区别。
I wrote a letter this morning.
I was writing a letter this morning.
It snowed last night. It’s all white outside now.
It was snowing last night, so it was very cold.
Mom was taling with Sue’s teacher when Sue entered the room.
2. When 与while的区别
( 1 ) when引导的时间状语从句中的动词可以是非延续性动词，也可以是延续性动词，而while从句中的动词必须是延续性动词。
I was watching TV when you called me.
It began to rain while we were waling in the par.
( 2 ) when说明从句动作和主句动作可同时发生，也可先后发生。而while强调主句动作在从句动作发生的过程中同时发生。
When the pot fell to pieces, the girl began to realie that she was not alone.
( 3 ) when或while引导的时间状语从句可以相互改写，但while引导的句子常用进行时态。
When they came in, the girl was dancing.
= While the girl was dancing, they came in.
( 4 ) while还可以做并列连词，意为“而，却”，表示“对比关系”，有轻微的转折之意。
She is very outgoing, while her sister is a little shy.