1, read the contents of the textbook first, understand the contents and knowledge points of this part, first browse 25 pages by yourself, see what is in the textbook, try to understand each example as much as possible, and mark what you don't understand.

2. Then preview page 26 and try to understand each example. Write down what you don't understand. Finally, preview page 27 and try to solve the problems that were not understood in the first two pages.