In high school, the teacher suggested buying it. The above problems are typical. As long as you understand the typical examples and review these problem-solving methods from time to time, you can strengthen your memory and try to remember. If you learn a problem, you can solve similar problems, so you are not afraid. Let me introduce you to the best way to learn mathematics (I am a high school student, and junior high school mathematics is not difficult, but I am talking about the learning method of senior high school mathematics, depending on my personal learning style): prepare a notebook, and the teacher will supplement questions during class. Generally, these problems are typical. Write them down and solve them at home. If you can't solve it, you can read it again. Sometimes there are many classic questions in math weekly and exercise books. The tactic of asking questions about the sea is not advocated, but it is undoubtedly a method to improve your memory step by step. In other words, this way is to strengthen your memory of problem-solving methods. That is what our teacher often says, "As long as you can do a problem, make it clear and make it clear, you are not afraid that they will give you a hundred words, a thousand words and ten thousand words."