Presenting the mind-map chart for the PAST CONTINUOUS to show how to form it and when to use it.
1) (LONG) ACTIONS AT A CERTAIN MOMENT IN THE PAST vs SHORT ACTIONS IN THE SIMPLE PAST.
I was watching TV when Mary telephoned.
2) SIMULTANEOUS ACTIONS IN THE PAST.
I was watching TV while John was reading the newspaper.
3) REPEATED ACTIONS IN THE PAST vs SINGLE ACTIONS IN THE PAST.
I was reading the book. vs I read the newspaper.