Singing three sighs, originally a term of music criticism, refers to one leading singer and three singing in chorus. This form of expression is simple and simple. Later, this word was used to describe the artistic effect of poetry. For example, the three overlapping chapters in the Book of Songs are actually "organized violence" imposed on folk songs. Because none of the ancient ballads preserved in various historical documents today is in the form of overlapping three chapters like the Book of Songs, and they all stop at one chapter. So now we mainly use the word "singing three sighs" to describe the beauty and charm of poetry.