1. The poem's ending couplet echoes the first couplet, which makes the whole poem form a complete and harmonious structure.
2. Tail couplets often keep the same rhyme feet and rhyming methods as the upper couplet, as well as similar tones and rhythms. This rhythmic beauty can enhance the phonological effect of poetry.
3. The poem's ending couplet forms a contrast or supplement with the upper couplet, and deepens the artistic conception and connotation of the poem through artistic techniques and rhetorical methods.