Past Continuous Tense (I was doing = S+was/were+Ving)
1. Study this situation:
        "Yesterday Karen and Jim played tennis. They began at 10 o'clock and finished at 11.30. So, at 10.30 they were playing tennis."
They were playing = "they were in the middle of playing." They had not finished playing.
Was / were -ing is the past continuous:
2. We use the past to say that somebody was in the middle of doing something at a certain time. The action or had already started before this time but had not finished:
        - This time last year I was living in Brazil.
        - What were you doing at 10 o'clock last night?
        - I waved to her but she wasn't looking.
        I started doing                                                I finished doing                Now
3. Compare the past continuous (I was doing) and past simple (I did)
4. We often use the past simple and past continuous together to say that something happened in the middle of something else:
        - Tom burnt his hand when he was cooking dinner.
        - I saw you in the park yesterday. You were sitting on the grass and reading a book.
        - While I was working in the garden, I hurt my bag.
I / he / she / it               was
We / you / they            were
Past continuous  (In the middle of action)
- I was walking home when I met Dennis.
- Ann was watching the television when the phone rang.
Past simple  (Complete action)
- I walk home after the party last night.
- Ann watched television a lot when she was ill last year.
I was doing