If you can't understand the examples, you don't really understand what you have learned. Learning is not reading novels. It's no use reading too much and not understanding it. In this case, we should learn advanced mathematics from the beginning, starting with textbooks and according to the standards of just going to college. The key point is to understand the knowledge points, learn the problem-solving skills of examples, and then treat after-school exercises as exercises. There is still a long time before the postgraduate entrance examination, step by step, and there is still time to review the whole book and real questions two or three times. You can also go to your brother and sister's senior three math class. Generally, there are timetables outside the classroom. Go and see for yourself or ask your brother and sister for it.