On the way to study, we must master our own learning methods, so as to achieve maximum efficiency. You need to form a good habit of previewing before class, so as not to understand.
Be sure to finish your homework on time after class. Write down what you don't understand in the notebook first, and then ask the teacher. If you do this for a long time, you will accumulate a lot of wrong questions, and it will be much easier when you review yourself.