The first-level title is the main chapter title in the paper, which is used to divide the text into larger parts or chapters. Numbers are usually numbered by numbers, letters or Chinese characters, such as "I" and "1". Wait. , and marked with a larger font size (such as bold No.4). The first-level title is exclusive to one line, which is located before the main content without punctuation at the end. The second-level title is the second-level section title under the first-level title, which is used to further subdivide the content of the first-level title. Numbers are usually numbered by numbers, letters or Chinese characters in brackets, such as "(1)" and "(1)", and marked with the same font size as the text. The second-level title is also an exclusive line, which is located after the first-level title and has no punctuation at the end.