The topics of concepts and formulas are the simplest topics in our usual exams. The test paper is divided into easy, medium and difficult (occasionally difficult) topics. As long as you remember the conceptual formula, you should have no problem with the easy questions. Difficult questions need to be flexibly used in formula, deformation, expansion, etc. This kind of problem needs to be solved on the basis of familiarity with formulas and concepts. As for the big problem you mentioned, there is a feeling of short circuit, which I think should be a "difficult" problem. This requires you to understand formulas and concepts, and at the same time, you need to comprehensively use all kinds of previous knowledge, use the conditions given in the topic to get the hidden conditions, see what conditions are needed for the final conclusion, analyze step by step, and slowly get the final result. Don't panic when you see the topic, it's a no-no. As long as you accumulate slowly, you will get better.