U字开头的单词或词组
unconcernedunpretentiousunmatchedunrulyunderageUFPuncannyundercutuneducatedunreflectingunfavorableunavoidableupdate nowuric acidundefined variableunwantedunfavourableundisturbedunbalanceunbalancedunsettleduninhibitedUNIXUruguayunder one's beltUCLunknowinglyundertakerunambiguoususerinfoU.S.S.R.unnamedunconditionalupwardupper caseundertookuncoveredunkindunresolvedunsurpassedunfathomableupturn
