I have been using Qidong math exercise book, and I feel very good. Qidong math exercise book pays attention to basic questions, basic knowledge and exercise difficulty, which is divided into three types with gradient. In particular, the exercises in the sixth chapter of linear equations are more suitable for students' self-study or parental guidance. You can't learn this chapter by following the textbook. When you use it, you will feel more doubts, which is its advantage. It's a good question to use it once.