Duality: A figure of speech in which two phrases or sentences with the same structure, equal number of words and symmetrical meaning are used to express opposite, similar or related meanings, which is called duality. Extended data duality usually refers to a rhetorical device consisting of two opposite phrases or sentences with the same number of words, similar syntax, level and related meanings. The dual relationship is close, concise and concentrated, and has strong generalization power; Formally, the front and back parts are uniform, the syllables are harmonious and disciplined. Strict. Duality also pays attention to simplicity and makes full use of Chinese tones.