We ____________ when the tornado _______ (sleep/hit)
We were sleeping when the tornado hit.
We ________ the loud sound of the thunders when we __________ cards (hear/play)
We heard the loud sound of the thunders when we were playing cards (hear/play)
What _____you ______when the earthquake ______? (do/start)
What were you doing when the earthquake started? (do/start)