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Jyutping bat1 bin6 suk6 mak6
Pinyin bù biàn shú mài

Definitions (Wiktionary)
  1. phrase, idiomatic
    to have no knowledge of practical matters; to be ignorant of practical matters

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Jyutping bat1 bin6 suk6 mak6
Pinyin bù biàn shū mài

Definitions (CC-CEDICT)
  1. lit. cannot tell beans from wheat (idiom); fig. ignorant of practical matters
Definitions (Wiktionary)
  1. phrase, idiomatic
    to have no knowledge of practical matters; to be ignorant of practical matters
Definitions (Kaifangcidian)
  1. (沒有對應漢語詞彙)