Wang Shizhen's Notes on Parting Gan Language said: "There were two kinds of rhymes in the Tang Dynasty. One is that the rough calendar has syllables, such as Lao Du's article "The city has a point and the people are worried, and the independent ethereal flying building" is also true; When a single sentence is awkward, even the sentences are awkward, like a palace merchant. For example, Xu Hun's "Clouds are beginning to sink, and mountains and rains are coming", and Zhao Wei's "Clouds emerge in Xiangtan at dusk, and the snow in Bashu disappears" is also true. "