The reasons for not updating in the past two days: 1. Implicit version - the end of the year, I have to prepare the materials for the year-end meeting, I am too busy and have no time. 2. The naked reality version - the author is lazy, and everyone is willing to guess. 3. The Ultimate Version -- Thinking about the way out of this book, the way out for individuals. Let me tell you here that if I am not a prisoner, this book will not be a prison. If you do the math, I owe you two chapters of 3,000 words and a chapter of 5,000 words. Let's see how much we can pay back tomorrow! (To be continued......)