a: did he give you a choice of options?
b: no, he offered me no ultimatum .
ultimatum
n. 最后通牒
a: ultraviolet light is harmful to our skin.
b: so you better wear some sunscreen when you are out in the sun.
ultraviolet
a. 紫外线的
a: were you all able to come to a unanimous decision?
b: no, one person disagreed with us.
unanimous
a. 全体一致的，一致同意的
a: i didn’t think that you would be able to carry the heavy box.
b: well, you shouldn’t have underestimated my strength.
underestimate
vt. 对……估计不足，低估
n. 估计不足，低估
a: i don’t understand the ideas that underlie your essay.
b: oh, let me explain them again.
underlie
vt. 构成……的基础（或起因），引起
a: what is the underlying reason for doing this journey?
b: to explore a new region of the country.
underlying
a. 含蓄的，潜在的
a: philip always undermines my opinions.
b: don’t worry, he is just trying to start an argument.
undermine
vt. 1。暗中破坏，逐渐削弱；2。侵蚀……的基础
a: even my underwear got wet in the rain.
b: that must have been a heavy shower.
underwear
n. 衬衣，内衣
a: doctor, do i really need to undress ?
b: well, i need to examine your back.
undress
vi. 脱衣服
vt. 除去……的衣服
n. ****（或半****）的状态
a: there is a high rate of unemployment in my region.
b: but i hear that it is not as bad as last year.
unemployment
n. 失业，失业人数
a: haven’t you finished the book yet?
b: no, the plot is just unfolding .
unfold
vi 1。展开，打开；2。显露，展现
vt. 展开，打开
a: let’s all sing a song.
b: do you think that will help to unify our group?
unify
vt. 1。使联合，统一；2。使相同，使一致
a: gavin unleashed some nasty comments at me.
b: don’t mind him, he is always rude.
unleash
vt. 1。发泄，发出；2。解带子放开
a: did you hear the latest news?
b: no, can you update me on the details?
update
vt. 更新，使现代化
n. 最新信息
a: you always stick to your word.
b: yes, i like to uphold my principles.
uphold
vt. 支持，维护，赞成，认可
a: there was an uprising in my country in the 1920s.
b: was that when you declared an independent nation?
uprising
n. 起义，暴动
a: there will be uproar if my homework is not submitted in time.
b: oh, but you are usually such a good student.
uproar
n. 吵闹，喧嚣，骚乱
a: i heard that some toxic uranium was dumped into the sea.
b: yes, it is shocking news.
uranium
n. 铀
a: there is a terrible smell of urine in this room.
b: i agree, but i don’t know where it is coming from.
urine
n. 尿
a: the usher directed me to the wrong seat.
b: oh, i think that he has just started the job.
usher
n. 引座员，招待员，迎宾员
vt. 1。引，领，陪同；2。预报（……的来到），宣告；3，创始，开辟
a: can we make this dish for dinner tonight?
b: no, i don’t have the right cooking utensils .
utensil
n. 器皿，器具