Mrs. White works in a middle school. She is a teacher. It is Sunday. She has no classes. At 10:00. She goes to a shop. There she buys a nice dress for herself. She puts it in her bag and then buys some cakes for her children. At 11:15, she gets home. She wants to put on her new, dress, but she can't find her bag. She telephones the shop assistant( 售货员). He says," I find three bags here. But which one is yours?"