All right. Zhou Chao, a famous architect, accurately predicted the exam and gave a detailed and targeted lecture. It divides knowledge points into four grades, namely B 1, B2, B3 and B4. B 1 is the highest score and can be recited at least twice. B2 is medium, just recite it skillfully, B3 is the lowest level, and you will have an impression after reading it once. B4 is a real problem built in previous years. You can practice it at any time after reciting it.