The investigation of mathematics is mainly about basic knowledge, and the difficult problems are only synthesized on the basis of simple problems. So the content in the textbook is very important. If you can't master all the knowledge in the textbook, you won't have the capital to learn by analogy.

You'd better preview the contents of the textbook before class. After class, we must do targeted exercises seriously and not be lazy. You can also repeat the examples in class several times when reviewing after class. After all, you should take notes in class.