Mathematics in senior high school is very difficult, and it is good for you to expand your thinking, because some problems in senior high school mathematics thinking training are not that you can't do it, but that your thinking can't get on. I suggest you buy a special topic of Longmen and practice your thinking. When doing the problem, don't just think about the result, think more about the process, why didn't you do it, think more about your own reasons, what you lack, and what ability you lack. I hope you can make good use of this book.