The past continuous is used to refer to actionA general term expressing that somebody or something does somethings in progressAn action is in progress when it is happening. E.g.: When I arrived he was surfing. ("he was surfing") at or around a particular point of timeA particular moment in time. E.g.: She came home at six. ("six") I was born in 1980. ("1980") in the past. This point can be implied, or expressed with a time expressionA word or group of words used in a particular situation. E.g.: Good morning, at six, on the sofa, or a clauseA group of related words containing a subject and a verb. with a verbA part of speech that expresses an action or a state. E.g.: John seldom plays tennis. in the past simple tenseA grammatical category that is marked by verb inflection. To express when an event or action happens in time or when a state exists, we use tenses.:

At 9 o'clock I was sitting on the train.
A few minutes ago they were still dancing.
When I called her she was studying.
What were you doing when you heard the explosion?
Sorry, can you repeat that? I wasn't listening. (i.e. when you said that)

Diagrams

Form: past continuous
Past continuous Past continuous for actions happening over a period of time in the past