was /were + doing，例如：
I was watching TV at 9 o’clock last night.
at 9 o’clock last night是时间点
They were playing football all afternoon.
at 8 o’clock last night, this time yesterday等。例如：
I was having lunch at home this time yesterday.
At that time she was writing a book.
1. This time yesterday I ____ ______（read）books.
2. At 9 o’clock last Sunday they ______ ______（have）a party.
3. When I _____（come）into the classroom, she ________ ______（read）a storybook.
4. She _____ ______（play）computer games while her mother ____ ______（cook）yesterday afternoon.
5. I _____ ______（have）a shower when you _______（call）me yesterday.
答案：1. was reading 2. were having 3. came; was reading
4. was playing; was cooking 5. was having; called