I feel like duolingo often teaches words I'll never use ... as some of the first words it teaches... why?
You mean fairies right? If so then of course! The legend of how the Vietnamese were conceived was that a fairy mother (Âu Cơ) fell in love with a dragon lord (Lạc Long Quân) and they had 100 children. 50 of them followed the father down to the sea while the rest followed the mother to the mountains.
If one must translate, I'd say they're closer to the Sihde of Irish lore than fairies of modern America (ie, not so much twinkly and magical as a separate group/culture existing alongside humans), so I'd say more fae than fairies, maybe? I don't know. It's all insufficient language borne of vastly differing cultures, regardless.
But yeah, the whole "con rồng, cháu tiên" thing definitely is a big part of Vietnamese lore. Seems like no history of Vietnam ever gets told without that phrase.
Well, it's called tàu cánh ngầm. :) https://vi.wikipedia.org/wiki/T%C3%A0u_c%C3%A1nh_ng%E1%BA%A7m
which one? phã, phả ? http://www.informatik.uni-leipzig.de/~duc/TD/td/index.php?bpos=1106459=ev
http://www.informatik.uni-leipzig.de/~duc/TD/td/index.php?word=pha=ve Oh, without an accent.