According to the query of Baidu question bank, "A knife will rust if it is not sharpened, and a person will fall behind if he doesn't learn" is a proverb about diligent education. This sentence emphasizes the importance of learning and education. If people are not educated, they will gradually fall behind others. It reminds people to keep learning and making progress to adapt to the development and changes of society.

Learning and education are important ways to acquire knowledge and skills. Through learning, people can understand the world, know themselves and master all kinds of knowledge and skills.