A typical example focuses on the exercises of junior high school mathematics, which is "Learning and Thinking: The Secret Book of the Finale of Junior High School Mathematics". According to relevant information, each topic includes three modules: skill refining, typical examples and real exercises. "Skill refining" summarizes the difficulties, mistakes and corresponding methods and skills in this topic; "Elaboration of Typical Cases" shows the main test sites involved in this question through carefully selected examples and the foreshadowing before the examples, so that students can understand the forms of difficult test sites; "True exercise" selects the mid-term exam questions and final exam questions of famous schools all over the country, so that students can consolidate and practice the methods and skills they have learned in time.