1, each sentence should be flush, the two sentences connected together should be flush, and the sentences connected together should also be flush, that is, "the sentences are flush, they are relative when connected, and they are glued together";
2. Except for the first pair and the second pair, the couplets in the middle must be couplets;
3. Generally speaking, rhyme must rhyme with the same level tone.
I guess someone wrote it on a whim.