Concept questions

[perla33]

Can everyone suggest/help to construct some concept questions for the following sentences:

1) I met John five years after he'd left the firm.

2) You should go on a diet.

3) The car was damaged in the accident.

4) I've lost my bag.

5) If I had studied harder, I would have passed my exams.

[Tdol]

As it's your task, why don't you start by putting what you think up?