[No. 1难点] 如何准确判断何时使用该时态。
①依据典型的时间状语有： at nine o'clock; last night; at this / that time yesterday; from 7 to 10 yesterday morning; the whole evening 等。
a. 在句型“主语＋was / were + V-ing + when + 主语 + V-ed”中, 表示“短”时间的动作用V-ed; 表示时间“长”的动作用“was / were + V-ing”。
The students were reading when the teacher came in.
b. 在句型“主语 + V-ed / was (were) + V-ing + while + 主语 + was / were + V-ing”中，由于while只能用于指一段时间，所以从句中的谓语动词必须是延续性动词，用过去进行时；而主句中的谓语动词如果是延续性的，则用过去进行时，如果是短暂性的，用一般过去时。
While I was watching TV, my sister was doing her homework.
While my mother was cooking, the telephone rang.
— You were out when I dropped in at your house.
— Oh, I was waiting for a friend from Nanjing at the train station.
[No. 2 易混点]一般过去时与过去进行时的不同点。
过去进行时常见时间状语在上面已作归纳，而一般过去时的典型时间状语有：yesterday (morning, afternoon, evening), last night(week, year等)，an hour ago, the day before yesterday, in 1999, long long ago等。
I got up at six this morning.
My mother was doing some washing the whole day last Sunday.
(1)表示感觉的动词，如：feel, hear, see, smell, taste等。
(2)表示状态、感情的动词，如：be, hate, love, like等。
(4) 表示所属关系的动词，如：own, belong等。
My father came home late.
My father was always coming home late.
1. — What you (do) at six this morning?
— I (water) those trees in the garden.
2. Yesterday I (write) a letter to my brother. I (write) a letter to Kate next week.
3. — What Peter (do) at this time yesterday?
— He (play) football with Simon.4. My mum (cook) supper when I got home yesterday.
5. Last night Grandma (tell) us a story before we (go) to bed.
6. Those boys (listen) to American pop songs from seven to nine last Monday morning.
1. We TV when the telephone .
A. watching, was ringing B. were watching, rang
C. watch, rings D. are watching, rang
2. The Reads lunch when I got to their house.
A. were having B. was having C. are having D. is having
3. When I got to the factory, the workers about the film.
A. are talking B. talked C. were talking D. have talked
4. What was Jim doing the teacher came in?
A. while B. and C. when D. but
5. I didn't think Simon saw me, he a sweater for his brother.
A. just chose B. was just choosing C. has just chosen D. had just chosen