阅读理解。 Almost everyone likes dogs, and almost everyone likes to read stories about dogs. I have a friend. He has a large police dog named Jack. Police dogs are very clever. Every Sunday afternoon my friend takes Jack for a long walk in the park. Jack likes these long walks very much. One Sunday afternoon a young man came to visit my friend. He stayed a long time. He talked and talked. Soon it was time for my friend to take Jack for his walk. But the visitor still stayed. Jack became very worried. He walked around the room several times and then sat down in front of the visitor and looked at him. But the visitor paid no attention to Jack. He went on talking. At last Jack got angry. He went out of the room and came back a few minutes later. He sat down again in front of the visitor, but this time he took the visitor's hat in his mouth. The visitor saw it and was surprised. He laughed and left. 1. — The young visitor stayed a long time, didn't he? — . [     ] A. Yes, he didn't B. Yes, he did C. No, he didn't D. No, he did 2. Jack became worried because . [     ] A. he wanted to go out for a walk B. he wanted to play with him C. he didn't know the young man D. he wanted to eat something 3. Jack sat down in front of the visitor because . [     ] A. he wanted the visitor to talk to him B. he wanted to talk with the young man C. he wanted to show the visitor how clever he is D. he wanted the visitor to leave 4. The visitor went on talking and . [     ] A. he paid no attention to his hat B. he didn't like Jack C. he didn't know that his hat was taken away by Jack D. he paid no attention to Jack 5. Jack went out of the room, but came back with in his mouth. [     ] A. food B. nothing C. the visitor's hat D. something