First of all, you should listen carefully in class. If you don't understand, don't worry. You can leave a mark if you don't understand. You can not only ask your teachers and classmates after class, but also ask them. Students have similar ways of thinking. Students should make you understand what you say. You can do some topics that you don't know. It's best to prescribe the right medicine and communicate with your classmates if you don't understand. Don't be discouraged. As long as you have a firm goal, you can certainly achieve it. I wish you success in the college entrance examination!