Top 1 building, your situation is really the reason why the foundation is not solid. You should belong to the kind of student who is very smart and immortal. Some places are good at math, while others are not good at it. If you master what you know in the exam, you will get high marks. If you get your less solid part, your grades will be unsatisfactory.

The suggestion is to analyze your own knowledge structure, find those knowledge points that have lost serious points, and then decompose them one by one, aiming at your weak modules, and reread this part of books and exercises.

Specific measures: prepare the wrong question book, the specific format is: wrong question+problem solving process+error analysis+harvest summary. Take time to look before each exam, and the foundation will be consolidated over time. My experience is very effective. )

I hope it helps you. I wish you progress in your studies and a happy New Year.