As you are a freshman, you have just started to learn your first book, and now you have just learned the limit. If you take the postgraduate entrance examination, I recommend the textbook and exercise "Topics in Mathematical Analysis Exercise Class", Xie Huimin, Yi Fahuai, etc. There is also Mathematical Analysis (4th Edition), which is both an exercise and a textbook, and it is very comprehensive. There are a lot of scores in the market, and there are many repetitions, which are basically endless. In addition, I can tell you directly that the textbooks for mathematics majors are not as concise as those for Grade One and Grade Two, and the main contents are two "definitions and properties". Theorem is also a property. It's important and difficult to learn to score three semesters and two semesters in high school. The first book you learn now should be almost a month's higher derivative. I'll give you a symbolic summary of the limit (function) of sequence (just master these): two definitions (δ-ε definition and geometric definition) and six properties (uniqueness, local boundedness, local sign preservation, pinching criterion, Cauchy convergence criterion, sufficient and insufficient operation of four operations). Continuity Remember two definitions, the definition of left-right limit and left-right continuity, the definition of uniform convergence, distinguish these two kinds of continuity, and remember that "closed interval continuity must be uniformly continuous". The proof of these theorems should be mastered. Then the six theorems of completeness of real numbers should prove each other. You should learn advanced algebra well, because you can't learn the second and third volumes well, and you can't learn abstract algebra, real variable function and functional analysis well in the following classes. If you think math major is difficult, you can consider changing your major, but you can't fail at the end of the year.