is used to talk about things which were in progress at, or during, a particular time in the past. Past simple is used to describe the past event, and the past progressive describes the unfinished situation:
At 9 o’clock I was watching a film on TV.
(focus: at 9 o’clock)
The car was running well during the journey.
(focus: during the journey)
2) is used for repeated actions over a past period of time:
Henry was going to evening dance classes when I met him.
He was trying to find a job in Singapore at that time.
They were often quarrelling with each other.
She was always working in her garden when we went to look
for him.