People sometimes like to read stories about dogs very much. They think that dogs are much cleverer than cats，sheep，cows or other animals in their homes.

    One of my close friends, Bob, has a very large police dog named Jack. Every Sunday afternoon, Bob takes Jack for a long walk in the park nearby. Jack likes it very much.

    One Sunday afternoon, I paid a visit to my friend. I stayed there for a long time and we had a long talk with each other. Soon it was time for them to take a walk in the park. We forgot that. Jack began to worry about it. He walked around the room several times and then sat down in front of me and looked at me.  But I still paid no attention(注意) to him. I went on talking with my friend. At last, Jack could not wait any longer. He went out of the room and came back a few minutes later. He sat down in front of me again. But this time, he held my hat in his mouth. Suddenly, I understood what Jack meant and so did my friend.