They were reading a book when mum came.
I was driving to work at 8 o'clock yesterday
You were sleeping when i called/
Who was playing the guitar when you came?
What were you doing at seben o'clock yeaterday?
When did granny make a cake?
What was granny making at ten this morning?
What's the time granny was making cake this morning?
Who was making a cake at ten this morning?
What was granny doing today?