1.What was the man doing when somebody knocked at the door?
2.What was he waiting for?
3.Who was skating?
4.When were the students dancing?
5.What was the girl eating when we came in?
6.Who was she looking after?
7.What were the pupils discussing?
8.When was the man passing the theatre?
9.When was it snowing?
10.How was the boy running?