2d Role-play the conversation.
Linda:  Mom, I'm really worried.
Mom:  Why? What's wrong?
Linda:  I can't find my schoolbag.
Mom:  Well, where did you last put it?
Linda:  I can't remember! I attended a concert yesterday so it might still be in the music hall.
Mom:  Do you have anything valuable in your schoolbag?
Linda:  No, just my books, my pink hair band and some tennis balls.
Mom:  So it can't be stolen.
Linda:  Oh, wait! I went to a picnic after the concert. I remember I had my schoolbag with me at the picnic.
Mom:  So could it still be at the park?
Linda:  Yes. I left early, before the rest of my friends. I think somebody must have picked it up. I'll call them now to check if anybody has it.