To put it simply, we can find that 60%-70% of the questions are basic, 20%-30% are moderately difficult, and about 10% are highly difficult, so the foundation is very important. So how to grasp the foundation? First of all, start with the textbook, which is the basis of all problems. Grasp the textbook, and you will succeed more than half. The second is to ask more questions, don't be embarrassed, as long as there is something unclear, ask until it is completely clear; Third, do more work, do more questions, do it with your brain, analyze the questions and summarize the questions. Questions that are well understood can be left out, and questions that are not understood must be understood; Finally, summarize more, remember the method if you do it right, and find the reason if you do it wrong. Learning is a very painful thing, you need to persevere, don't shrink back when you encounter difficulties, have confidence in yourself, remember, you will succeed!