Learning to Use the Past Continuous Tense

The Core Characteristic of the Past Continuous tense is that it is used to focus on the time period of a completed action in order to provide more details about what was happening during that event.

In Diagram 1, the Reference Point (R) of I was eating my dinner (expressed in the Past Continuous) is a specific time in the past, when the action of eating was on-going.  As you can see from the diagram, the sentence doesn't tell us when the extended action began or ended. What we do know, is that the action coincided with the time of 6pm.

You can also say that an action was ongoing for a certain amount of time in the past. The statement, I was running for two hours, can only be used when the whole activity is in the past - the run started and finished in the past.  We know that the action took two hours, Reference Point (R), although the sentence doesn't tell us when the action began or ended. 

One of the main functions of Past Continuous is to enable the speaker to describe parallel events. The Past Continuous is considered to be a narrative tense as it is used when the speaker wants to tell a story about something that happened in the past. As you know, during a narrative, the speaker needs to explain multiple events and in order to keep the story straight, needs to ensure that the listener understands the sequence of events - which events happened first, which happened simultaneously, and which events took longer to complete than others. The Past Continuous is used to show the length of activity and used to show how multiple activities fit into one narrative.