Second, it is conducive to the echo of the paper. With the outline, we can establish the concept of the whole, and test the position and function of each part from the perspective of the whole, whether there is a logical connection between them, whether the space occupied by each part is commensurate with its position and function in the overall situation, whether the proportion between each part is appropriate and harmonious, whether every word, sentence, paragraph and part is needed by the overall situation, and whether it is coherent and coordinated into a whole. After such thinking and writing, the structure of the paper can be unified and complete, and it can serve the expression of the content of the paper well.