The Past Continuous tense

We use the Past Continuous :

1. —for an action which was in progress at a stated time in the past. 

      (we don’t know when the action started or finished)

  I was reading a magazine at 5 o’clock yesterday.

2. —for a longer action which  was in progress when another shorter action interrupted it.

  She was studying (longer action) when the phone rang. (shorter action).

3. for two or more actions which  were happening  at the same time in the past. (simultaneous actions)

  Tina was doing the washing-up while the children were playing in the garden.

4. —To give background information in a story. 

  The sun was shining brightly  as  Tom was driving his brand new car            through the city centre.     (* Touchstone 4 - pp.6-7)