If you want to focus on the competition students, the book "Excellence Competition" written by Huang Dongpo is a good choice, which contains a lot of competition questions and previous mid-term exam questions, but this book is limited to high-level students. Of course, it is no problem for ordinary students to try, but it takes some effort and it is still somewhat difficult. Doing more questions can improve your thinking level. The topic of "experimental class" is relatively simple, and teachers in general schools will let students buy it. For top students, Huang Dongpo's textbook is still recommended.