"Firecrackers" versus "gongs and drums": nouns are dual and even. "Sound" versus "explosion": The reduplicated words are opposite to each other, even the words are harmonious. "Word" versus "should": Verbs are antithetical, regardless of hierarchy. "Old" and "new": Nouns are opposite to each other, and even words are interrelated. "Year" and "Year": Nouns are opposite and equal. The upper alliance bid farewell to the old and welcome the new.
From the perspective of parallelism, in order to meet the requirements of parallelism, a pair of couplets must abide by the four basic principles of "bytes should be parallel and alternate", "words should be parallel and opposite", "the last word of the upper couplet should be receivable" and "the last word of the lower couplet should be receivable". The familiar Spring Festival couplets "two years old one night, five classes for two years" meet these requirements.
Part I: (Ping) Ping/Ping/Ping/Ping.
The bottom line is: (a)/(a) Ping/ (a) ping.
Among them, the position of brackets, that is, words in odd positions, can be wider. There is a saying called "135, no matter what, 246 is clear".