A few days ago my wife sent me out to buy something. When I came home, I handed  her a paper bag and said, "Here are the apples you wanted." She looked in the bag, and then she looked at me. "I told you," she said slowly, "to buy some eggs." I felt worried about my _ , so I went to see a doctor. He was a very kind man. "I have seen many people like you. It's nothing to worry about," he said. "If you know you are absent-minded, you are all right. But if you do not know you're absent-minded, you may be really in trouble." "Many famous people were absent-minded," the doctor told me. "Thomas Edison was standing in line  one day to pay his taxes . When he arrived at the window, he found that he had forgotten his own name. He had to ask the man who was behind him to tell him who he was." I felt much better and got up to leave. "Thank you, doctor," I said. "How much do I have to pay you?" "Ten dollars for the check-up ," the doctor said. "But doctor, I did not have a check-up!" For a moment the doctor looked puzzled. Then he said, "Oh, yes, it was the patient before you who had a check-up. How absent-minded I am!" The doctor took Edison's story for example   _  .
to show absent-mindedness is common among people because he liked telling stories to make the author laugh to make fun of Edison