comme il fautyoudaoicibaDictYouDict[comme il faut 词源字典]
1756, French, literally "as it should be;" from comme "as, like, how," from Old French com, from Vulgar Latin quomo, from Latin quomodo "how? in what way?," pronominal adverb of manner, related to quam "how much?," qui "who" (see who).[comme il faut etymology, comme il faut origin, 英语词源]