16 Before the postgraduate entrance examination, many people were full of praise for the complete works of Li Yongle. At that time, it was said that Zhang Yu's question was too difficult. 16 said after the postgraduate entrance examination that the real questions of Li Yongle's complete works were too shallow, and Zhang Yu's questions could dig the essence of mathematics. 16, Zhang Yu became the biggest winner of the mathematics postgraduate entrance examination. His question is more difficult and obscure. 16, math problems are more difficult, so students who use Zhang Yushu are more calm when facing the exam. My personal suggestion is, take math one, remember the previous foundation of high mathematics, and use Zhang Yu. I forgot the basics of mathematics before, so I used Li Yongle. Take Zhang Yu's lecture 18 as an example. The first example is the nature of implicit function. If we don't have an intuitive and clear understanding of limit and differential, it takes time to understand implicit function, which is useless in the short term. After using Li Yongle's book to brush 660 questions, he also has a copy of Beyond 135 and a copy of 400 Questions. These two books are as difficult as Changyu. You can get high marks by reading these three books through. After completing 1000, Zhang Yu has the last eight sets of papers and the last four sets of papers.