U字開(kāi)頭的單詞或詞組
unconcernedunpretentiousunmatchedunrulyunderageUFPuncannyundercutuneducatedunreflectingunfavorableunavoidableupdate nowuric acidundefined variableunwantedunfavourableundisturbedunbalanceunbalancedunsettleduninhibitedUNIXUruguayunder one's beltUCLunknowinglyundertakerunambiguoususerinfoU.S.S.R.unnamedunconditionalupwardupper caseundertookuncoveredunkindunresolvedunsurpassedunfathomableupturn