quien sabeyoudaoicibaDictYouDict[quien sabe 词源字典]
"Originally and frequently in Spanish-speaking contexts: ‘Who knows?’, ‘who can tell?’", Mid 19th cent.; earliest use found in Robert Fitzroy (1805–1865), hydrographer and meteorologist. From Spanish quién sabe who knows from quién (interrogative pronoun) who + sabe, third person singular present indicative of saber to know.[quien sabe etymology, quien sabe origin, 英语词源]