If the foundation was poor before, make it up. I think mathematics is actually mainly done. Look at the examples in the book first, and then find exercises to do. I feel that if I learn new content, teachers will not listen too carefully in the new class in the future, and each teacher's teaching methods are different. If I study now, the teacher may not adapt. The most important thing is to do exercises, then revise and think. It is better to have a wrong set of questions. . Next semester, you can borrow what you want to learn, flip through books by yourself, and then have tutorials on the internet or something. . Preview yourself first. .