Abstract is a style different from research papers, which is composed of understanding, sorting, comprehensive analysis and evaluation after researchers read the literature on a certain topic in advance. The purpose of the review is to reflect the new level, new trends, new technologies and new discoveries of a certain discipline. From its history to present situation, existing problems and development trend, we should make a comprehensive introduction and comment. On this basis, I put forward my own opinions, predict the development trend of technology, and lay a good foundation for topic selection and opening. Second, the format of literature review The format of literature review is different from that of general research papers. This is because the research papers focus on the research methods and results, while the literature review introduces the detailed information, trends, progress, prospects and comments related to the theme. Therefore, the format of literature review is relatively diverse, but generally speaking, it includes the following four parts: preface, theme, summary and references. When writing a literature review, you can write an outline according to these four parts, and then write according to the outline. The preface mainly explains the purpose of writing, introduces related concepts and definitions, outlines the scope, and briefly explains the current situation or focus of debate of related topics, so that readers can have a preliminary outline of the problems to be described in the full text. The theme part is the main body of the summary, and the writing methods are diverse and there is no fixed format. It can be summarized in chronological order and compared from different angles according to different problems. No matter which format is adopted, the collected documents should be summarized, sorted, analyzed and compared, and the historical background, present situation and development direction of related topics and comments on these issues should be made clear. In the theme part, we should pay special attention to representative, scientific and creative references and comments. The summary part, similar to the summary of the research paper, briefly summarizes the theme of the full text, puts forward my own opinions and predicts the further development direction. Iii. Literature review is defined as 1. In order to make the project report have sufficient basis, master students are required to make a literature review before the project is started. 2. In the literature review, graduate students should systematically consult the domestic and foreign literature related to their own research direction. Read at least 30 documents at ordinary times. 3. In the literature review, graduate students should explain the development history of their research direction, the main research achievements of predecessors, existing problems and development trends. 4. Literature review should be clear and concise. 5. Use data appropriately and reasonably. The document quotation is enclosed in square brackets [] and placed in the upper right corner of the quotation. 6. I have my own opinions and opinions on literature review. Encourage graduate students to find more problems, ask more questions, and point out possible ways to analyze and solve problems. 7. Literature review shall be no less than 3,000 words. IV. Precautions 1. Collect documents as completely as possible. Mastering a large number of comprehensive documents is the premise of writing a good summary, otherwise it is impossible to write a summary by collecting a little information casually. 3. Pay attention to the representativeness, reliability and scientificity of the cited documents. There may be similar views in the collected documents, and the reliability and scientificity of some documents are not the same, so we should pay attention to choosing representative, reliable and scientific documents when quoting documents. 3. Cite documents faithfully.