Question

He's always busy at work, and shows no interest in his child. (不~不~) CCP 20

Accepted Answer

只知道忙自己的工作，对孩子的事从来都不闻不问。不~不~ used with two monosyllabic adjectives or location words with opposite meanings to indicate something is "just right," or sometimes used to indicate a dissatisfying intermediate state. It is also used with antonymic monosyllabic verbs or morphemes to indicate "if not... will not...," or used with two monosyllabic synonyms as an emphatic form of "not."

Front	He's always busy at work, and shows no interest in his child. (不~不~)
Back	只知道忙自己的工作，对孩子的事从来都不闻不问。不~不~ used with two monosyllabic adjectives or location words with opposite meanings to indicate something is "just right," or sometimes used to indicate a dissatisfying intermediate state. It is also used with antonymic monosyllabic verbs or morphemes to indicate "if not... will not...," or used with two monosyllabic synonyms as an emphatic form of "not."
Page	CCP 20

Monosyllabic Or Busy Work Shows Interest Child 不~不~