One day,while I was reading an interesting book,my father came in and asked me to buy a bottle of beer for him.I went downstairs and rode on my bike.When I reached the shop,I entered without locking my bike.A few minutes later,I came out of the shop.Suddenly I saw a man riding on my bike and trying to get away with it.I quickly ran to him.But he was too fast.I couldn't catch up with him.Just then,a police car happened to come along.I went over and asked them for help.They hurriedly drove after the thief.A bike can never run faster than a car.So the thief is caught in no time.I got my bike back again.