AN ACTION WAS HAPPENING IN THE PAST AND INTERRUPPTED BY ANOTHER ACT...

2/ An action was happening in the past and interruppted by another action or two actions were

happening at the same time

As/when + past simple , S+V ( past continuous

While S+ V( past continuous) S+ V ( past continuous)

Ex :

My brother was playing football when my mother came

While my mother was cooking my father was reading newspapers