Jane’s mother was about seventy, and Jane and her husband wanted to give the old lady a nice present for her birthday. She liked taking tea, so Jane bought a small electric machine( 电器 ). It could make tea and then wake you up in the morning. She brought it to her mother on her birthday, and s howed her how to use it. “Before you go to bed, put tea and water in it,” she explained to her mother, “and don’t forget to turn the electricity on. When you wake up in the morning, your tea will be ready.” After a few days, the old lady telephoned her daughter and said, “Jane, there is one thing I don’t understand. Why do I have to go to bed to make tea? Can’t I have tea in the afternoon or in the evening?”