In order to prepare for the high school mathematical physics competition, I learned a lot of advanced mathematics knowledge, such as calculus, Euler function, spatial analytic geometry and so on. After actually learning this, high school mathematics looks very simple, just like going to high school and looking back at junior high school. The way of thinking about some problems is much deeper, more thorough and clearer than that of simple high school students. Moreover, the college entrance examination made it clear that there is nothing wrong with solving problems with knowledge above senior high school-that's for sure, and that's why mathematical theory should be judged wrong.

But I also agree that learning high school mathematics well is the foundation of advanced mathematics, and learning advanced mathematics really takes a lot of energy. If you have enough energy and do well in high school mathematics, then look at advanced mathematics. But don't take it as a main course, because after all, most knowledge is not involved in the college entrance examination.