Textbooks are the best. Don't use the reference book in a hurry. You just crossed the line. I don't think I used it at first. Listen carefully to the teacher's explanation first, write down the questions, don't copy the teacher's answers, understand them by yourself, write them after class, and then write them out, and then find a reference book to find a topic to consolidate. Don't use reference books in a hurry. Textbooks are the most basic. If you don't even know the reference books, will you? Do the textbook questions well first. I think five years and three years is a difficult book, and I use it more in senior three. Read Xue Jinxing's book first. Where is the summary, where is the innovation and transformation of the questions, you will get almost everything. Then look at the college entrance examination questions and innovative questions in five years and three years.