This is really your own problem, because you don't pay enough attention to the exam or pay too much attention to it, which is also the reason why you are prone to make mistakes in the exam. In high school, teachers often said that we should do the questions like exams, and the exams should do the questions as usual. This is not to say that we should despise the exam, but to say that we should not be too nervous during the exam and fully relax ourselves. But the exam is an exam, not a holiday. We should keep a moderate sense of tension and make our nerves excited. Only in this way can we better grasp the topic. Besides, I want to give you a suggestion. Usually, you should be nervous when doing problems, such as math 120 minutes exam time. Usually, when you do the problem, you should finish it within 100- 105 minutes (this should be done as formally as in the exam, and then answer the question after you finish it, just like in the exam. You can't take chances, because you won't slack off if you're not in the exam. You should finish it in 150 minutes. Only by cultivating your tension in peacetime can you be more comfortable in the exam!