To write the chapter "Introduction" well, the first thing is to do a good job in literature retrieval, collection and research. With a solid foundation of literary work, a clear understanding of the subject and a clear goal of catching up with the highest level of the subject, we can master various tools and means to carry out research. Chapter 1 is essentially the result of the author's literary work. In other words, chapter 1 is also a science, and the writing of chapter 1 cannot be completed without research.

The task of literature work is to clarify the background and significance of the research topic, investigate the history and present situation of the research topic, understand the current level of the topic, and decide the content and implementation of doctoral thesis research. Accordingly, in chapter 1 of the doctoral thesis, firstly, the research background and significance should be well written, secondly, the history and present situation of the subject should be well written, and thirdly, the main research contents of the doctoral thesis should be explained.