Subtitles of paper topics are commonly found in literary papers, medical or scientific research papers, because such papers generally contain relatively long fixed phrases, such as chemical proper nouns, disease names, full names of literary works and so on. The general format of the subtitle of the thesis requires that when the thesis topic is too long to be further simplified, we split the topic, taking the main research content as the theme, the secondary and limited research scope as the subtitle, and the main and subtitle are divided into two lines.