I think I should read the questions carefully, I have made mistakes on this point. For example, the question wanted me to say something about the action of enzymes, so I supposed to explain how enzymes work. However, I described the trend of the graph. I need to answer questions with more specific answers, such as more accurate and more comprehensive description.
The most important thing is to review more carefully before the exam, after all, this can make me more calm and confident in the exam.