University knowledge is not useless, but divorced from practice in the process of education, so it will give students the impression that it is useless and difficult to learn. In fact, professional courses (especially engineering majors) learned at school are bound to be used at work, unless I don't work in this major like me. As far as my major in applied electronics is concerned, I need to study analog electricity, digital electricity, sensor principle, electromagnetic field and electromagnetic wave, integral transformation and so on. These courses are theoretical, very abstract, and also quite test the level of mathematics. At that time, even the students with the best grades said that they still didn't know what these things were, so they didn't find them useful at all.