Rhyme can be divided into _ _ and _ _.

Metric poetry originated from Shen Yue of Qi Yongming in the Southern Dynasties, which paid attention to rhythm and antithesis. They were shaped in Shen Quanqi and Song Wenzhi in the early Tang Dynasty and matured in the prosperous Tang Dynasty. Rhyme requires the unity of the number of words in the poem, and each poem is five-character, six-character and seven-character sentences, which are referred to as five laws, six laws and seven laws, among which six laws are relatively rare. The usual metrical poems stipulate 8 sentences each. If there are only six sentences, it is called Xiaofa or Sanyun poem; More than 8 sentences, that is, 10 sentences, are called exclusive laws or long laws. Usually eight sentences are completed, and every two sentences form a couplet, which is counted as a quadruple. It is customary to call the first couplet a title couplet, the second a antithetical sentence, the third a neck couplet and the fourth a sentence ending couplet. The upper and lower sentences of two or three couplets (namely, parallel couplets and neck couplets) of each song must be antithetical sentences. Except for the first pair and the second pair, the couplet in the middle must be double. The dual requirements of secondary laws are more extensive. Rhyme requires the whole poem to rhyme, and the rhyme is limited; The second, fourth, sixth and eighth sentences rhyme, the first sentence can be put on or off, and the words of each rhyming sentence are flat. There are "flat rise" and "flat rise" in the upper and lower sentences. In addition, the metrical requirements of metrical poems also apply to quatrains.