The formula for couplets Ping and Ze: "Ping to Ze, Ze to Ping, Ping and Ze must be distinguished clearly; regardless of one, three or five, distinguish two, four or six."
Including:
1. Ping and oblique appear alternately in this sentence.
2. Ping and Chi exist in opposition in the couplet. For example: "The golden sands and water are warm against the clouds and cliffs, and the iron cables across Dadu Bridge are cold." The equivalence of these two lines is "Ping Ping Ping Ping Ping Ping Ping Ping Ping Ping Ping Ping Ping Ping Ping Ping Ping Ping Ping Ping.
The couplets require the harmony of levels and obliques and harmonious tones. The traditional custom is "廄 rises and flat falls", that is, the last word of the first line is in the square tone, and the last word of the second line is in the flat tone.
Methods for pairing couplets:
First, the number of words must be equal and the sentences must be consistent. Unless the position of a certain word is intentionally left vacant to achieve a certain effect, the number of words in the upper and lower couplets must be the same, no more, no less.
Second, the levels must be consistent and the tones must be harmonious. The traditional custom is to use the oblique tone at the end of the first line and the level tone at the end of the second line.