1. The number of sentences is fixed
Each rhythmic poem usually has eight sentences. If it exceeds eight sentences, it is called arranged rhythm or long rhythm. A rhythmic poem with eight lines, every two lines form a couplet, totaling four lines. It is customary to call the first couplet the first couplet, the second couplet the jaw couplet, the third couplet the neck couplet, and the fourth couplet the tail couplet. The upper sentence of each couplet is called a sentence, and the lower sentence is called a couplet. The two sentences form a couplet relationship; the relationship between the couplet of the preceding couplet and the sentence of the following couplet is called the relationship of adjacent sentences.
2. Strict rhyme
Rhymed poetry usually rhymes with flat tones, and must rhyme according to the words in the rhyme book. In principle, only the original rhyme can be used, not the adjacent rhyme; even if it is a little looser, only the first sentence that enters the rhyme is allowed to use the adjacent rhyme, which is called "borrowing rhyme". Rhymed poetry also requires that the whole poem rhymes with one rhyme, that is, one rhyme to the end, and no rhyme changes are allowed in the middle. The second, fourth, sixth and eighth lines rhyme, and the first line may or may not rhyme.
3. Pay attention to the level and obliqueness
There are regulations on the sentence pattern and the obliqueness of the words in each line of the rhymed poetry: pay attention to the adhesion and harmony. Rhythm poetry in the broad sense allows loss of adhesion, but rhythm poetry in the narrow sense does not allow loss of adhesion. "Losing cohesion" means violating the rule that the second character of the sentence in the following couplet and the second character of the couplet in the preceding couplet must be the same. Although Chinese has four tones, in rhymed poetry, it is not necessary to distinguish the four tones like lyrics and music. It only needs to be roughly divided into two tones: level and oblique.
4. Contradiction is required
Contradiction means that the syntax must be the same. For example, the first sentence of the first couplet of "Lv Ye Shu Huai" has no predicate, and the second sentence also uses a predicate-free sentence pattern. The sentence pattern of the first sentence of the chin couplet is "subject, predicate, object, object", and the next sentence also uses the same sentence pattern. The same sentence pattern is used in the neck couplet; the same words cannot be used in the antithesis. Contradictions such as "people have joys and sorrows, and the moon waxes and wanes" are allowed in lyrics and music.