There was a famous writer named Han Yu in the Tang Dynasty in China. He studied in his hometown when he was a child. One day, the teacher gave each student a copper coin to go shopping and see who could fill a room. After school, all the students went to the market. The next day, some people bought saplings, others bought bamboo ... but no one could fill a room with things. The teacher was disappointed. After a while, Han Yu came. I saw him take a candle out of his sleeve and light it. The candle lit up the whole room at once. When the teacher saw it, he was so happy that he said again and again, "Good! All right! Han Yu is really smart! "