Mr White was over 80 years old, but he looked younger than his age. He played Tai Chi in the park every day, so he was very healthy. It was 11:30. It was time for him to walk home. He usually got home thirty minutes later. One day, Mr White didn't get home when it was 12：30. His family worried about him. After a short while, a police car stopped in front of their house. What happened?

    "The old man was lost and he called us for help," the policeman said.

    When the policeman left, Mr White's daughter asked her father, "Dad, you go to the park every day. How can you be lost?" "I'm not lost at all. I'm just tired. I don't want to go home on foot," answered Mr White with a smile.