Nancy and Li's classes are better than Li's. Li's teaching style is more relaxed and humorous, and the explanation of the course content is more vivid and interesting, which is easy to arouse students' interest. Nancy's class is more serious and seems more boring, so Nancy and Li's class is better than Li's. Professor Li's courses mainly focus on sexual knowledge and skills. Including sexual psychology, health, education and so on. Its course content is rich, covering many aspects from theory to practice, so that students can acquire comprehensive knowledge and skills in this field.