U字開頭的單詞或詞組
USAunableup to nowup-to-dateulcerative colitisunfortunatelyunexpectedlyU-turnustinultimatelyusingunitaryunrecognized commandunderlyingunityUFOuncertaintyup to dateuntitledubiquitousU.K.uncertainuserunlessuptakeundermineunpackunder wayUnited Nationsurnupside downunderstandingunblockupsideUNOumpunauthorizedUHFunfortunateunveilundertakeunrestrained