1. Poetic style name. There are four sentences in each song, with five words in each sentence called Five Elements and seven words called Seven Rhymes. Some people say six words per sentence. Or use flat rhyme, or use rhyme. There are two kinds of quatrains: modern quatrains and ancient quatrains. Modern quatrains began in the Tang Dynasty, came into being after metrical poems, and were formed by covering half of metrical poems, so they are also called "truncated sentences". In fact, archaic quatrains are the shortest archaic poems, which came into being before metrical poems, and Yutai Xinyong already contains archaic quatrains. Ancient quatrains written by poets after the Tang Dynasty are generally called ancient quatrains. 2. Refers to the sentence whose context is cut off. Wang Songpu's Selection of People in Tang Dynasty: "In December of the 16th year of Kaiyuan, imperial academy made a toast:' I don't know what this means. Every time I try to post, I will take the end of the first year and the end of the month. From now on, examiners will try to post a plain text to save the ceremony. "Jude's sentence. It means reading broken sentences according to the meaning of the text. "Zhuzi School" Volume 52: "What about Yichuan's quatrains of' being as straight as possible'?" Yue's The Analects of Confucius: "At seventy, do what you want from your heart without overstepping the rules": "When the word' heart' is a quatrain."