This afternoon, I got on a bus and sat at the back of the bus. Five minutes later, the bus stopped and seven or eight people got off. Suddenly I saw a wallet under a seat. I picked it up and asked the bus driver to help me find its owner（主人）. I asked all the people on the bus, but they said it wasn't theirs. Suddenly（突然）an old man got on the bus again and asked about the wallet. He looked very worried. At that moment I knew he was the owner. I gave the wallet back to him, and he thanked me again and again.
