The past continuous tense is used to describe an action which was in progress (unfinished) at a particular time in the past.
Form and Use
(Positive form) - Subject + "to be" + verb present participle
(Negative form) - Subject + "to be" + not + verb present participle
(Questions) - "to be" + Subject + verb present participle
I was working.
He was eating his dinner when the phone rang.
The dog next door was barking last night while we were trying to sleep.
He was not working when I saw him.
I wasn't playing games on the PC, I was doing my homework.
Were the children watching TV when you got home yesterday?
Were the other guests already eating when you arrived at the party?
Action and Non-Action Verbs
Non-Action verbs - for example, those describing feelings, states and possession - are not used in a Past Continuous form (the rules and exceptions are the same as those for Present Continuous). We normally only use 'action' verbs with the Past Continuous.
Use of Past Continuous
Describing a background action
The past continuous tense is frequently used when we are telling a story. We use the past continuous to describe an action which was already in progress in the past when another action or event occurred. The second event is described with a past simple form.
Question: What were you doing when I phoned you? Answer: I was reading a newspaper when you called.
Question: Were you living in Italy when you met your wife? Answer: No, I met my wife while I was working in London.
We can also use two past continuous forms to describe two actions that were in progress at the same time. In this case, we usually link the two continuous verbs with 'when', ''while' or 'and'.
While I was washing my car, a boy fell off his bicycle.
We were driving home when we saw the accident.
I was reading my book and Michaela was cooking dinner.
Actions in progress at a specified time in the past
We use the past continuous when we want to explain or ask about what people were doing at a specific time in the past.
Question: What were you doing yesterday? Answer: I was helping my friend repair his car.
Question: What were you doing at midnight last night? Answer: I was sleeping, of course!
Temporary States in the Past
We can also use the past continuous to talk about states which were temporary in the past.
In 2004 I was working in London.
I was staying at the Hilton Hotel in Paris when I met Paul.
Habits in the past (with 'always')
When we talk about past habits, we generally use "Used to". However, if we want to emphasize that an action happened frequently, or constantly, we can do this by using "always" with a past continuous form. "Always" is placed between "to be" and the main verb. See the examples below:
Were you a good student at school? No, I was always getting into trouble for being late, or forgetting my homework!
This example explains that the action (getting into trouble) happened frequently / repeatedly / constantly.
I separated from my wife because we were always arguing.
This example also explains that the action (arguing) happened frequently.