My friend has a big police dog named Kim. Police dogs are often very smart. Every Sunday afternoon my friend takes Kim for a long walk in the park. Kim likes walking very much. One Sunday afternoon a man visited my friend. He talked to my friend a long time. They talked and talked. Soon it was time for my friend to take Kim for his walk, but the man still stayed. Kim became very worried about his walk in the park. He walked around the living-room sometimes and at last sat down in front of the man and looked at him. But the man went on talking. After thirty minutes, Kim couldn't stand  it. He went out of the room and came back a few minutes later. He sat down in front of the man again but this time he held the man's hat in his mouth. The story is about   _  .
dogs cats people a police dog