There is a story about Li Bai. He was not a very hard-working student when he was young. He often skipped school(逃学).
One day when he was walking by the river, he saw an old woman. She was working on a large piece of iron(铁).
Li Bai asked, "What are you doing?"
She said, "I'm making a needle(针). "
"But how can you make a large piece of iron into a needle?"
She replied, "I must work hard every day. "
Li Bai suddenly understood the importance of hard work, and he started to work hard at school.
What can we learn from the story?(no more than 15 words)