In fact, my experience in learning mathematics is very simple, that is, I have to do it myself. One more thing, we must grasp the key points. When I took the postgraduate entrance examination for the first time, my goal was actually to get high marks, so I read books very carefully. I took the time to look at all the details, so that I didn't have time to do the simulation later (the lack of time at that time was also related to playing games myself). Later, I learned that in fact, the math exam is those questions, which will always be the focus, that is, multiple integrals, functions, mean value theorems, quadratic forms, parameter estimation ... Looking through the previous questions, the exam has not changed much, and other unimportant places will never be tested. If you are unfortunately admitted, it will be only a few points, and it is not worth making great efforts at all, because it is a small loss.

To sum up, it is a word, mathematics should be done in person, and key problems should be done more.