If the foundation is poor, I suggest that you make up the foundation first and review the textbook from the beginning, which will help you understand and expand your thinking, and it will be very helpful for doing problems in the future. When reviewing, you should be clear-cut, often contact the contents of the previous chapters, and learn a course that is not impetuous or greedy. I have read the textbook for the National College Entrance Examination 149 more than three times. Hope useful to you