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.