The simplest and most effective way is to do the problem. You will say that you can't do it, and you will do it if you can't do it. If you can't do it, look up the book to understand the relevant knowledge points and do it. If you don't know how to read those books again, you really won't ask teachers and classmates. Don't ask them at the beginning, but you will understand all the relevant questions before you do it. So you will know a series of questions and do more questions. It's not too late to go to senior one.