Some math problems are more difficult, and some problems are difficult for the candidates by the teacher. As for the review materials, you can buy Yun Fei's textbooks, which are really good. I just bought it from his house. It's really good! Also, whether you want to go to cram school depends on your level. If you think you can handle the college entrance examination, there is no need to enroll in a remedial class. If you feel that your level is limited, you'd better sign up for a remedial class. I introduce Yun Fei to the remedial classes for the college entrance examination. Many of my classmates signed up for this class, and the response was excellent.