uncertain/uncertainty
uncertain/ʌnˈsə:tn/adj.(［反］certain) 1.易变的，靠不住的：a person of uncertain character摇摆不定的人；uncertain weather变化无常的天气2.不确知的，不能断定的：be uncertainof/abo···
uncle
uncle/ˈʌŋkl/n.［c］1.叔，伯，舅，姨夫，姑夫：Your uncle is the brother of your father or your mother.你的uncle是你父亲或母亲的兄弟。2.儿辈对父辈的一般称呼：Uncle Sam山姆大叔(口语···
uncomfortable/uncomfortably
uncomfortable/ˈʌnkəmˈfɔ:təbl/adj.(［反］comfortable)不舒服的，不自在的：feel uncomfortable感到不自在These shoes are really uncomfortable.这些鞋穿起来确实不舒服。uncomfortably···
unconditional
unconditional/ˈʌnkənˈdiʃənəl]/adj.无条件的，绝对的：unconditional transfer无条件转移The victorious army demanded unconditional surrender.胜方要求敌人无条件投降。
unconstitutional
unconstitutional/ˈʌnkɔnstiˈtju:ʃənəl/adj.违反宪法的：The prospect for passage of the bill was somewhat cloudy, in view of its being evidently unconstitutional.由于这个议案明···
unconscious/unconsciously/unconsciousness
unconscious/ʌnˈkɔnʃəs/adj.(［反］conscious) 1.失去知觉的，神志不清的：He lay unconscious for some hours.他昏迷了好几个小时。2.未意识到的，无意识的：He is unconscious of his mi···
uncover
uncover/ʌnˈkʌvə/vt.1.揭露：uncover their tricks揭露他们的阴谋诡计；uncover criminal activities揭露犯罪活动2.揭开：uncover the lid of a kettle揭开水壶盖子
under
under/ˈʌndə/ I.prep.1.在…的下面(表示位置)：under the skin在皮下；under the bridge在桥底下(比较：below the bridge在桥下方) Don’t stand under a tree during a thunderstorm.雷雨时···
undercover
undercover/ˌʌndəˈkʌvə/ adj.暗中进行的，秘密做出的，私下的：undercover payments贿赂(暗中给的钱)；an undercover police operation秘密警察行动A federal judge upheld the undercove···
underdeveloped
underdeveloped/ˈʌndədiˈveləpt/adj. 1.(国家等)经济不发达的；发育不全的：underdeveloped nations不发达国家；underdeveloped kidneys发育不全的肾It’s in the underdeveloped eastern ···
