Simple past vs past continuous

Front

Hello Anna, what _______ (you / do) when I called you last night?

Back

were you doing

Front

While they were watching TV, their kids ________(sleep)

Back

were sleeping

Front

I was listening to the radio when you ________(call) me.

Back

called

Front

When he opened the window, it __________ (snow).

Back

was snowing

Front

Her plane didn't landed yet when we________ (arrive) at the airport.

Back

arrived

Front

She met them at the station while she _________ (wait) for her train.

Back

was waiting

Front

We use past continuous

Back

For an action that was happening during a time in the past

Front

While she was talking to her boss, her mobile phone _________ (ring).

Back

rang

Front

We use the past simple for....

Back

For an action that started and ended in a concrete moment of the past

Front

We were walking in the mountains when we_________ (see) a strange animal.

Back

saw