Self-study is no problem and necessary, because if you don't study by yourself, even if you go to the remedial class, you still can't understand it. I have this kind of counseling in my high school now, and I am very experienced! And now the books are complete and the topics are good. For example, the (Olympic Classic) series, or many books published by Zhejiang University are good. If you are ambitious and have plenty of time, you can also subscribe to the magazine (Secondary Mathematics), which is the best one, even if it is a little too much, it is also difficult. Subscription address: Editorial Department of Secondary Mathematics, No.241,Weijin Road, Hexi District, Tianjin