The book divides the learning process into 21 days (15 days of study + 3 weekends of review). It is a vivid presentation of HSK Grammar class. In the book, there are guidance on the preparation of class for helping students summarize the key and difficult points of grammar; blackboard writing of teachers for a systematic interpretation of grammar to help students understand and grasp the complicated grammar points with intuitive icons; and exam-level training exercises for students to exercise repeatedly so as to gain new knowledge by reviewing old.