To sum up, Mr. Fang Hao teaches really well, and I am very grateful to meet this teacher. He is really the best graduate math teacher I have ever heard. I can add what other teachers said. Some people may say that this year's paper does not have so many knowledge points, which is abnormal. Don't expect all awesome methods to be just auxiliary functions. It doesn't matter how well you use it. Finally, the most important thing is to do more questions and train more videos. It's just the key to the auxiliary function, and a good video can really reduce your study time.