ultimate = 至極的，最終的update = 更新，更新換代unable = 無能為力unauthorized = 未經授權unclear = 不明確underbrush = 灌木叢undergo = 遭受undersecretary = 副秘書長undoubted = 毫無疑問的uneasy = 不安的unsafe = 不安全的up to = 至upcoming = 即將到來的upgrade = 升級usher = 引座員
