The past continuous is formed from the past tense of be with the -ing form of the verb:
We use the past continuous to talk about the past:
for something which continued before and after another action:
The children were doing their homework when I got home.
I got home. The children did their homework.
The children did their homework when I got home.
As I was watching television the telephone rang.
This use of the past continuous is very common at the beginning of a story:
The other day I was waiting for a bus when …
Last week as I was driving to work …
for something that happened before and after a particular time:
It was eight o’clock. I was writing a letter.
At eight o’clock I wrote some letters.
In July she was working in McDonald’s.
.to show that something continued for some time:
My head was aching.
Everyone was shouting.
for something that was happening again and again:
I was practising every day, three times a day.
They were meeting secretly after school.
They were always quarrelling.
with verbs which show change or growth:
The children were growing up quickly.
Her English was improving.
My hair was going grey.
The town was changing quickly.