The result of education in China, ten years of hardship, is true! You go out early and come back late ... You are not a mathematician, so it's really useless to study so deeply. Schools can be used as a kind of knowledge for non-mathematicians to understand, without being the basis for assessment! Don't be confused, you are like this, everyone is the same, so you should actively face the immediate problems, find solutions, and contact frequently when you have time to help you provide reference opinions!