阅读理解

Old John went to see a doctor. The doctor examined him（检查）and said, “Medicine（药）can't help you. You must have a good rest. Go to a quiet place for a month, go to bed early, drink some milk, walk a lot and smoke one cigar（雪茄烟）a day.”

“Thank you very much,” said Old John, “I want to do everything you say.”

A month later old John came to the doctor again. “Well,” said the doctor, “I'm glad to see you. You look much younger.”

“Oh, Doctor,” said Old John, “I feel quite well now. I had a good rest. I went to bed early, I drank a lot of milk, and I walked a lot. Your advice（建议）certainly helped me. But you asked me to smoke one cigar a day, and the one cigar a day nearly killed me at first. It's no joke（玩笑） to start smoking at my age.”