What is the rhyme of the first sentence of the poem?

There are strict rules on rhyme in modern poetry, which can be summarized as follows: the first sentence can be put or taken off, and the next sentence must be put on rhyme. 3 1. Even rhymes: 2468 rhymes in metrical poems and 24 rhymes in quatrains. Whether it is a metrical poem or a quatrain, the first sentence may or may not rhyme. For example, to judge Han Zuo (Du Mu) in Yangzhou. There is water in the green hills, and the vegetation in the south of the Yangtze River is withered in autumn. Where does the Jade Man teach oral sex at Bridge 24 on a moonlit night? The first 124 sentence rhymes. Another example: Leyou Tomb (Li Shangyin), with a twilight shadow in my heart, I have opened it in Leyou Tomb. Sunset, infinitely beautiful, only near dusk. The first sentence doesn't rhyme, but two or four sentences rhyme. Generally speaking, it is common that the first sentence of five-character poems does not rhyme, and it is also common that the first sentence of seven-character poems rhymes.