The use of high numbers in freshmen may vary from university to university and from major to major, but they are generally two volumes of high numbers from Tongji University, and some use three volumes of high numbers from Peking University. I like the three volumes of Advanced Mathematics of Peking University very much, which were written by Wen Li and Wu. The three volumes of Advanced Mathematics published by Peking University can be said to be a classic set of books. If you learn well, it will be very helpful for the postgraduate entrance examination.