If you pass, then, 1, you must listen carefully in class. If you don't understand, ask after listening. Of course, it's best not to ask and solve it yourself. This is the teacher's help to reshape your mathematical thinking habits.
2. Know what your problem is, train in a targeted way, and don't memorize difficult questions, because if you haven't solved a problem for a long time, you will not do it next time if you look at the answer.