I think what the teacher said is useless because the teacher has never taught us how to use knowledge. Some people may want to know how to use what they have learned and need to learn. Anyway, I feel that if I don't teach how to use knowledge, I just don't know how to use it. People in China take too many things for granted. People in China take it for granted that everyone can make full use of their knowledge by engraving the knowledge points in their minds. But the fact is that there have been "useless" scholars and "nerds" in China since ancient times. Many times we are inexperienced. Because when the objective conditions change, experience will be invalid.