First of all, there is not much to learn in the elective books. Do more problems and practice frequently, and you can reach a certain level. General multiple-choice questions are easier to get more than 10.

Compulsory, involving a wide range of knowledge, and they are all interrelated, such as trigonometric functions, involving too many questions, multiple-choice questions, fill-in-the-blank questions, and big questions. If you don't learn that part well, there may be problems in the process of doing the problem.

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