U字開(kāi)頭的單詞或詞組
ulcerunreachable codeupper caseuncoveredultimatumuntrueundersupplyunrelatedunder controlunderageultravioletunit of measureUADunlinkunsurpassedunfilledutilitarianismUGTun-Americanupstartunicycleunloadingunfreeupkeepunderwaterunidentified flying objectuncouthunaccustomedunsuccessfulupside-downunreasonableUPSup in armsunhandleduneaseuberunimportantuser nameundercoverunholyunorganizedutensil