One is to find a school teacher to recommend it in the class, and the other is to publish workbooks for a long time to keep the style and difficulty coefficient consistent, because different students have different learning levels and need workbooks with different difficulty coefficients. As a teacher, I always recommend exercise books from the difficulty coefficient. Generally speaking, it is easiest to practice with textbooks in class. Secondly, I don't advertise. In the market, the difficulty coefficient of those workbooks is usually fixed, and they will be published as long as they are published.