undoubtedly
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B2 adverb /ʌnˈdaʊtɪdli/

undoubtedly

毫无疑问
Meaning
without a doubt, certainly
Example
He is undoubtedly the best player on the team.
他毫无疑问是队里最好的球员。
C2 adjective /ʌpˈrɔːr.i.əs/

uproarious

极其滑稽
Meaning
Extremely funny or noisy; causing loud laughter or commotion.
Example
The comedian's jokes were absolutely uproarious.
喜剧演员的笑话绝对是极其滑稽的。
B1 adjective /ʌnˈfeər/

Unfair

不公平; 不正当;
Meaning
not right or just; treating people in a way that favors some over others
Example
It's unfair to blame her for something she didn't do.
指责她做了她没有做的事是不公平的。
B2 adjective /ʌnhaɪˈdʒiːnɪk/

Unhygienic

不卫生的；缺乏适当的卫生
Meaning
not clean; lacking proper sanitation
Example
The restaurant was closed due to unhygienic conditions in the kitchen.
由于厨房不卫生的条件，餐厅被关闭。
A2 noun /ʌmˈbrɛlə/

umbrella

伞
Meaning
A device used for protection against rain or sun, typically consisting of a collapsible canopy mounted on a central rod.
Example
She opened her umbrella as it started to rain.
下雨时她打开了她的伞。
C1 adjective + noun ʌnˈpresɪdentɪd ˈnɒlɪdʒ

unprecedented knowledge

前所未有的知识
Meaning
Information or understanding that has never been obtained or achieved before.
Example
Artemis will provide unprecedented knowledge about the solar system.
阿尔忏将提供关于太阳系的前所未有的知识。
C1 adjective /ʌnˈɡɑː.dɪd/

Unguarded

不设防的
Meaning
not protected or defended; careless about revealing private thoughts or information
Example
In an unguarded moment, she revealed her true feelings about the project.
在一个不设防的时刻，她揭示了她对这个项目的真实感受。
C1 verb /ˌʌndərˈsɛl/

undersell

Meaning
to sell something at a lower price than competitors or to downplay the value of something
Example
The shop undersold its rivals by offering huge discounts.
B1 adjective /ˌʌnɪkˈspektɪd/

Unexpected

出乎意料的; 令人惊讶的
Meaning
not expected or anticipated; surprising
Example
The unexpected news left everyone speechless.
出乎意料的消息让所有人都哑口无言。
C2 noun /ˌjuːnɪˈtɛəriən/

unitarian

一神论者
Meaning
A person who believes that God exists as one entity rather than as a Trinity; a member of a religious denomination that emphasizes individual freedom of belief.
Example
The Unitarian church is known for its inclusive and open-minded approach.
一神论教会以其包容和开放的思想方式而闻名。
C1 adjective /juːˈbɪkwɪtəs/

ubiquitous

无处不在
Meaning
Existing or being everywhere at the same time.
Example
Social media has become ubiquitous among young people.
社交媒体在年轻人中变得无处不在。
B1 adverb /ʌnˈjuːʒuəli/

unusually

异常地
Meaning
in a way that is not typical or expected; to an uncommon degree
Example
It was unusually cold for this time of year.
对一年中的这个时候来说，天气异常寒冷。
C2 adjective /ʌnˈspɛərɪŋ/

unsparing

无情的
Meaning
Showing no mercy or generosity; harsh or severe.
Example
The critic was unsparing in his review of the play.
评论家在他的剧评中毫不留情。
C2 noun /ˈɜːrtʃɪn/

urchin

街头小孩
Meaning
a mischievous or poorly dressed child, often from the streets
Example
The ragged urchins played by the riverbank.
那些穿着破烂的街头小孩在河边玩耍。
C1 noun /ˈʌndərˌwɜːrld/

underworld

地下世界
Meaning
The criminal world of organized crime or the mythical world of the dead.
Example
The detective spent years studying the secrets of the underworld.
侦探花了很多年研究地下世界的秘密。
B1 adjective /ʌnˈsɜːrtən/

Uncertain

不确定
Meaning
not able to be relied on; not known or definite; not having reliable knowledge
Example
I am uncertain about my future career plans.
我对未来的职业规划感到不确定。
B2 verb ˈjuːnɪfaɪ

unify

统一
Meaning
To make or become united, uniform, or whole; to bring together into a single unit.
Example
Adolescents unify with peers for social acceptance.
青少年为了社会接纳与同伴统一。
C1 verb /ʌpˈruːt/

uproot

拔除
Meaning
To pull something out of the ground; to remove or displace completely.
Example
They uprooted the old tree from the garden.
他们从花园里把老树拔了出来。
C2 adjective /juːˈnɪsənənt/

unisonant

和谐的
Meaning
Sounding together or in harmony.
Example
The unisonant voices created a powerful effect.
和谐的声音创造了强大的效果。
B2 adjective /ʌnˈberəbəl/

Unbearable

无法忍受
Meaning
too painful, annoying, or unpleasant to tolerate; impossible to endure
Example
The heat in the desert was unbearable.
沙漠中的热度是无法忍受的。
B2 adjective /ʌnˈfɪt/

Unfit

不适合; 不适当;
Meaning
not in good physical condition; unsuitable or inappropriate
Example
He was declared unfit for military service due to his poor health.
由于健康状况差，他被宣判不适合军事服务。
B2 adjective /ʌnˈrɪəl/

unreal

不真实的
Meaning
not real or not based on reality; exaggerated or imaginary
Example
The experience felt unreal after the sudden news.
突如其来的消息后，这种经历感觉不真实。
B2 noun /ˈɜː.dʒən.si/

Urgency

紧急
Meaning
the quality of requiring immediate action or attention; pressing importance
Example
The urgency of the situation required immediate medical attention.
情况的紧急性要求立即的医疗关注。
A1 adverb /ʌp/

up

向上
Meaning
towards a higher position or level
Example
He climbed up the ladder quickly.
他迅速爬上了梯子。
B2 adjective /ˈʌt.ɚ/

Utter

完全的; 绝对的; 全部的
Meaning
complete; absolute; total
Example
The movie was an utter disaster at the box office.
这部电影在票房上完全失败了。
C1 adjective /ʌnˈtaɪmli/

Untimely

不合时宜
Meaning
happening at an inappropriate or inconvenient time; premature
Example
His untimely death at the age of thirty shocked everyone.
他的过早死亡在30岁时震惊了所有人。
C1 adjective /ʌnˈskeɪðd/

unscathed

毫发无损
Meaning
Without suffering any injury, damage, or harm.
Example
She escaped from the accident unscathed.
她毫发无损地逃离了事故。
C1 adjective /ˌʌnɪmˈplɔɪəbəl/

unemployable

不适合就业
Meaning
Not able to be employed; lacking the skills or qualities necessary for employment
Example
Due to his criminal record, he was considered unemployable in most companies.
由于他的犯罪记录，他在大多数公司被认为是不适合就业。
C2 noun /juːˈkeɪs/

ukase

法令
Meaning
An authoritative decree or order, especially one issued by a sovereign or government.
Example
The czar issued a ukase restricting the freedom of the press.
沙皇发布了一项限制新闻自由的法令。
B2 adjective /ʌnprɪˈpɛrd/

Unprepared

未准备好
Meaning
not ready or able to deal with something
Example
He was unprepared for the difficult exam.
他对困难的考试毫无准备。
B1 adjective /ˌʌnsəkˈsesfl/

Unsuccessful

失败的; 没有成功的;
Meaning
not achieving desired aims or results; failing to accomplish a purpose
Example
His unsuccessful attempt to climb the mountain left him disappointed.
他未能成功登上山顶，感到失望。
A2 noun /ˈjuːzər/

user

用户
Meaning
a person who uses or operates something
Example
He is a frequent user of this app.
他是这个应用程序的常用用户。
C2 adjective /ˌʌnɪmˈpiːtʃəbl/

unimpeachable

无可指摘
Meaning
Not able to be doubted, questioned, or criticized; completely trustworthy.
Example
She is known for her unimpeachable honesty.
她因其无可指摘的诚实而闻名。
C1 adjective /ˌʌnɪˈkwɪvəkəl/

unequivocal

明确
Meaning
Leaving no doubt; clear and unambiguous
Example
She gave an unequivocal answer to the question.
她对问题给出了明确的回答。
C1 adjective /ʌnˈsoʊld/

unsold

未售出的
Meaning
not sold; remaining without a buyer
Example
The unsold goods were returned to the warehouse.
未售出的商品被退回仓库。
B1 adjective /juːˈniːk/

Unique

独特的; 唯一的; 稀有的
Meaning
being the only one of its kind; unlike anything else
Example
Every snowflake is unique in its pattern.
每一片雪花在它的图案中都是独一无二的。
B2 adjective /ʌnˈɡreɪt.fəl/

Ungrateful

忘恩负义
Meaning
not feeling or showing thanks for something done or given; not appreciating kindness
Example
She felt he was ungrateful for all the help she had given him.
她觉得他对她给予的所有帮助都忘恩负义。
B2 adjective /ˌʌnəˈweər/

Unaware

无意识的; 不知道的; 没有意识
Meaning
not knowing or realizing; having no knowledge of something
Example
She was completely unaware of the danger.
她完全没有意识到危险。
B2 noun /ˈʌndərkləʊðz/

underclothes

内衣
Meaning
Clothing worn beneath outer clothes, such as underwear or lingerie
Example
He folded his underclothes neatly before packing them.
他在打包前把内衣叠得整整齐齐。
B1 adjective /ʌnˈlaɪk/

Unlike

不同的; 不相似的
Meaning
different from; not similar to
Example
Unlike his brother, he prefers quiet activities.
与他哥哥不同，他喜欢安静的活动。
C2 adjective /ʌnˈwəʊntɪd/

unwonted

不寻常
Meaning
Unusual, uncommon, or out of the ordinary.
Example
She spoke with an unwonted gentleness that surprised everyone.
她以一种不寻常的温柔说话，令所有人都感到惊讶。
A2 verb /ʌpˈdeɪt/

update

更新
Meaning
to make something more modern or current; to provide new information
Example
Please update your software regularly.
请定期更新您的软件。
B2 adjective /ˈjuː.nɪ.faɪd/

unified

统一
Meaning
Made into a whole or joined together.
Example
A unified approach fosters better outcomes.
统一的方法促进了更好的结果。
C2 verb /ʌnˈfrɒk/

unfrock

剥夺神职
Meaning
To remove a priest from his position or deprive someone of a rank.
Example
The corrupt priest was unfrocked after the investigation.
腐败的牧师在调查后被解除职务。
C1 adjective /ʌnˈkɛmpt/

unkempt

邋遢
Meaning
Having an untidy or disheveled appearance.
Example
He looked unkempt after sleeping outdoors all night.
他睡了一整晚露天后，看起来邋遢。
C1 adjective /ʌnˈkleɪmd/

Unclaimed

未认领的; 未要求的; 被遗弃或无主的
Meaning
not claimed by anyone; not demanded or requested; abandoned or ownerless
Example
The unclaimed luggage was stored in the airport's lost property department.
未认领的行李被存放在机场的失物招领处。
B2 adjective /ˌʌn.kəʊˈɒp.ər.ə.tɪv/

uncooperative

不合作的
Meaning
not willing to help or work with others; unhelpful
Example
The witness was uncooperative and refused to answer questions.
证人不合作，拒绝回答问题。
C2 adjective /ʌkˈsɔːriəs/

uxorious

过度宠爱妻子
Meaning
excessively fond of or submissive to one's wife
Example
He was so uxorious that he agreed with everything his wife said.
他是如此的宠爱妻子，以至于同意了妻子说的每一件事。
A2 noun /ˌʌpˈsteəz/

Upstairs

楼上
Meaning
on or to an upper floor of a building; the upper floor or floors
Example
She went upstairs to her bedroom to rest.
她上楼去她的卧室休息。
C1 verb /ʌnˈɜːθ/

unearth

发掘
Meaning
To dig up from the ground or to discover something hidden.
Example
Archaeologists unearthed ancient artifacts at the site.
考古学家在遗址发掘了古代文物。
C1 adjective ˌʌn.pəˈtɜːbd

unperturbed

不为某事烦恼或困扰；冷静且镇定
Meaning
Not worried or disturbed by something; calm and composed.
Example
She remained unperturbed despite the challenges.
尽管有挑战，她依然保持冷静。
B2 verb /ˌʌndərˈɛstɪmeɪt/

underestimate

低估
Meaning
To judge something as less important or smaller than it really is.
Example
Never underestimate the power of teamwork.
永远不要低估团队合作的力量。
C1 noun /ˈʌndərˌteɪkər/

undertaker

殡葬员
Meaning
A person whose job is to prepare the dead for burial and arrange funerals.
Example
The undertaker prepared the body for the funeral service.
殡葬员为葬礼服务准备了尸体。
C1 verb /ˈʌndərkʌt/

undercut

Meaning
to sell at a lower price than a competitor; to weaken or undermine something
Example
The company tried to undercut its rivals by offering lower prices.
B1 noun /ˈjuːs.fəl.nəs/

Usefulness

有用性
Meaning
the quality of being useful; practical value or helpfulness
Example
The usefulness of this tool became apparent during the project.
这个工具的有用性在项目过程中变得显而易见。
C1 adjective /ˌʌnfɔːrˈsiːn/

unforeseen

Meaning
Not anticipated or predicted; unexpected.
Example
The project faced unforeseen challenges that delayed its completion.
B2 adjective /ʌnˈskɪld/

Unskilled

无技能的; 无技术的工人
Meaning
lacking technical training or ability; not requiring special skills
Example
Many unskilled workers are looking for training opportunities.
许多没有技能的工人正在寻找培训机会。
C2 adjective /ʌnˈblʌʃɪŋ/

Unblushing

厚颜无耻的; 放肆的
Meaning
showing no shame or embarrassment; boldly shameless
Example
He told the unblushing lie without any hesitation.
他毫不犹豫地说了那个无耻的谎言。
B2 noun /ʌnˈkɒnʃəsnəs/

unconsciousness

无意识
Meaning
the state of being unaware of and unable to respond to one's surroundings
Example
After the accident, he was in a state of unconsciousness for several hours.
事故后，他昏迷了几个小时。
B2 verb /ʌnˈfəʊld/

unfold

展开或打开
Meaning
to open or spread out something that was folded; to gradually reveal or develop
Example
She unfolded the letter carefully.
她小心地展开了信件。
C2 adjective /ʌnˈflæpəbəl/

unflappable

冷静沉着
Meaning
calm and composed, especially in difficult situations
Example
Despite the crisis, he remained unflappable and confident.
尽管面临危机，他依然保持冷静沉着，充满自信。
B2 adjective /ʌnˈprɒf.ɪ.tə.bl̩/

Unprofitable

无利可图
Meaning
not yielding profit or gain; not producing financial benefit
Example
The unprofitable business was forced to close down after three years.
这个无利可图的生意在三年后被迫关闭。
B1 adjective /ʌnˈklɪər/

unclear

不清楚
Meaning
not easy to understand; vague or ambiguous
Example
The instructions were unclear, so I asked for clarification.
说明不清楚，所以我要求澄清。
C2 adjective /ˌʌnsɛrəˈmoʊniəs/

unceremonious

不拘礼节/粗鲁
Meaning
Done without formality or courtesy; abrupt or rude.
Example
He made an unceremonious exit from the party.
他从派对上不拘礼节地离开。
C1 verb /ˌʌndərˈsteɪt/

understate

低估
Meaning
To describe something as being less important or serious than it really is.
Example
He tends to understate his achievements.
他倾向于低估自己的成就。
B2 adjective /ˌʌnɪnˈfɔːrmd/

uninformed

不了解情况的
Meaning
lacking knowledge or awareness about a particular subject; not educated or informed
Example
The decision was made by an uninformed committee.
这个决定是由一个不了解情况的委员会做出的。
B2 verb /ˌʌndərˈteɪk/

undertake

承担
Meaning
to commit to and begin a task or project; to take on responsibility
Example
She decided to undertake a challenging project.
她决定承担一个具有挑战性的项目。
C2 noun /ˈʌndərlɪŋ/

underling

下属
Meaning
a person of low rank or importance; a subordinate
Example
The manager ordered his underlings to finish the task quickly.
经理命令他的下属快速完成任务。
C1 adjective ʌnˈmætʃt

unmatched

无与伦比
Meaning
Not equaled or rivaled by any other; without equal.
Example
The freedom fighters showed unmatched bravery.
自由战士们展示了无与伦比的勇气。
B1 adjective /ˌʌndərˈstændəbl/

understandable

可以理解的
Meaning
Able to be understood; reasonable or justifiable.
Example
Her reaction was understandable given the situation.
考虑到情况，她的反应是可以理解的。
C2 verb /ˈʌndərˌraɪt/

underwrite

Meaning
To guarantee financial support, especially by agreeing to cover losses or risks; in insurance, to assess and accept risks.
Example
The bank agreed to underwrite the company's new bond issue.
C1 noun /ˈʌndərˌɡɑːrmənt/

undergarment

内衣
Meaning
a piece of clothing worn under outer clothes, usually next to the skin
Example
He bought new undergarments for the wedding.
他为婚礼买了新的内衣。
B2 noun /ˈʌndərˌteɪkɪŋ/

undertaking

事业
Meaning
A task, project, or responsibility that someone agrees to do.
Example
Starting a new company is a difficult undertaking.
创办新公司是一项艰巨的事业。
C2 noun /ˈjuːnɪvəˌlɛns/

univalence

单价性
Meaning
The state of having a single valence or combining power, especially in chemistry.
Example
Hydrogen is characterized by its univalence in chemical reactions.
氢气在化学反应中以其单价性为特点。
C2 noun /ˈʌmbrɪdʒ/

umbrage

冒犯，愤怒
Meaning
A feeling of resentment or offense.
Example
She took umbrage at his rude remark.
她对他的粗鲁言论感到愤怒。
B1 adjective /ˌʌnbɪˈliːvəbəl/

Unbelievable

难以置信
Meaning
impossible to believe; extremely surprising or remarkable
Example
The magician's performance was absolutely unbelievable.
魔术师的表演简直令人难以置信。
C1 adjective /ˌʌnrɪˈfaɪnd/

unrefined

未精炼的
Meaning
not processed or purified; lacking polish or sophistication
Example
The unrefined oil must be processed before it can be used as fuel.
未精炼的石油在用作燃料之前必须进行加工。
C2 adjective /ʌnˈtʃeɪst/

Unchaste

不道德的; 不纯洁的;
Meaning
not celibate; having engaged in sexual relations; lacking moral purity
Example
The conservative society considered her behavior unchaste and improper.
保守的社会认为她的行为不道德和不合适。
C1 adjective /ˈʌpərˌmoʊst/

uppermost

最高
Meaning
situated at the highest place or most important
Example
Her family's safety was uppermost in her mind during the crisis.
她在危机期间心里最重要的是家庭的安全。
C2 noun /ˌjuːzɜːrˈpeɪʃən/

usurpation

篡夺
Meaning
The act of taking someone's power or property illegally or by force.
Example
The general's usurpation of the presidency led to political unrest.
将军对总统职位的篡夺导致了政治动荡。
C2 noun /ˈjuːzjuːfrʌkt/

usufruct

使用权
Meaning
The legal right to use and enjoy the benefits of someone else’s property without owning it.
Example
The tenant had the usufruct of the land but not its ownership.
租户有权使用这片土地，但没有所有权。
B1 verb /juˈnaɪt/

unite

联合
Meaning
to join together or combine; to bring people or things together
Example
The crisis helped unite the community.
危机帮助团结了社区。
A2 adjective /ʌnˈtaɪdi/

Untidy

凌乱的; 无序的;
Meaning
not neat or orderly; messy and disorganized
Example
Her untidy room was filled with clothes scattered everywhere.
她凌乱的房间充满了四处散落的衣服。
B1 verb /ˈʌpˌɡreɪd/

upgrade

升级
Meaning
to raise something to a higher standard, improve
Example
We decided to upgrade the software to the latest version.
我们决定将软件升级到最新版本。
B2 adjective /ˌʌnkənˈvɪnsɪŋ/

Unconvincing

不可信
Meaning
failing to persuade or impress; not believable or credible
Example
His excuse for being late was completely unconvincing.
他因迟到而给出的借口完全不可信。
B2 adjective /ˌʌnkənˈtroʊld/

uncontrolled

无法控制的
Meaning
not restrained or managed; lacking control
Example
The wildfire spread in an uncontrolled manner, causing widespread damage.
野火以无法控制的方式蔓延，造成广泛破坏。
C1 noun /ʌnɪmˈpɔːrtəns/

unimportance

不重要
Meaning
the state or quality of being insignificant or not important
Example
He dismissed the issue with a sense of unimportance.
他以無關緊要的態度忽略了這個問題。
B2 adjective /ʌnˈkwɒl.ɪ.faɪd/

Unqualified

不合格的; 无资格的;
Meaning
not having the necessary skills or qualifications; complete or absolute
Example
He was unqualified for the engineering position due to lack of experience.
他因缺乏经验而不适合这个工程职位。
B2 adjective /ˌʌnəˈveɪləbəl/

unavailable

不可用
Meaning
Not able to be obtained, reached, or used; not present or accessible.
Example
The manager was unavailable to take calls during the meeting.
经理在会议期间不可用，无法接听电话。
A2 verb /ʌpˈset/

upset

烦扰
Meaning
to make someone worried, sad, or angry; to disturb
Example
The bad news upset everyone.
坏消息 upset 每个人。
C1 noun /ˈʌndərˌstʌdi/

understudy

替身演员
Meaning
An actor who learns another's role to act as a replacement if needed.
Example
The understudy performed when the lead actor fell ill.
当主角生病时，替身演员上场表演。
C1 noun /juːˈtoʊpiə/

utopia

乌托邦
Meaning
An imagined perfect society or place where everything is ideal.
Example
Many philosophers dreamed of creating a utopia for humanity.
许多哲学家梦想着为人类创造一个乌托邦。
C2 adjective /ɜːrˈbeɪn/

urbane

都市的
Meaning
showing polished manners, refinement, and sophistication
Example
He was an urbane gentleman who charmed everyone at the party.
他是一个都市绅士，在派对上迷住了所有人。
B2 adjective /ʌnˈtʃeɪndʒəbəl/

Unchangeable

不可改变的; 固定的;
Meaning
not able to be changed or altered; fixed and permanent
Example
The laws of physics are unchangeable principles that govern the universe.
物理法则是不变的原则，支配着宇宙。
B2 adverb /ʌnˈwɪlɪŋli/

unwillingly

不情愿地
Meaning
in a way that shows reluctance or lack of desire; not willingly
Example
She unwillingly agreed to attend the meeting.
她不情愿地同意参加会议。
C1 adjective /ʌnˈkwes.tʃən.ə.bl̩/

Unquestionable

无可争议的; 确定的
Meaning
not able to be disputed or doubted; certain and beyond doubt
Example
Her honesty and integrity are unquestionable qualities.
她的诚实和正直是无可争议的品质。
C2 adjective /ʌnˈstɪntɪŋ/

unstinting

慷慨的
Meaning
given generously without holding back
Example
She received unstinting support from her family.
她从家人那里得到了慷慨的支持。
A1 noun /ˌjuːnɪˈvɜːrsɪti/

university

大学
Meaning
an institution of higher education and research, which grants academic degrees
Example
She is studying law at the university.
她在大学学习法律。
B2 adjective /ʌnˈfeɪv(ə)rəbəl/

unfavorable

不利
Meaning
not beneficial or advantageous; showing disapproval or opposition
Example
The proposal received an unfavorable response from the committee.
提案收到了委员会的负面回应。
C2 adjective /ˌʌn.rɪˈdʒɛn.ər.ət/

unregenerate

顽固
Meaning
Not reformed or showing no signs of change; stubbornly refusing to reform or repent.
Example
He remained an unregenerate opponent of progress.
他仍然是进步的顽固反对者。
C1 adjective ʌnˈwɔːr.rən.tɪd

unwarranted

不合理的
Meaning
Not justified or necessary; without good reason.
Example
His anger toward the staff was completely unwarranted.
他对员工的愤怒是完全不合理的。
C1 adjective /ʌnˈkuːθ/

uncouth

粗鲁
Meaning
Lacking good manners, refinement, or grace; awkward or rough.
Example
His uncouth behavior shocked the guests at the party.
他粗鲁的行为让聚会上的客人感到震惊。
C1 noun /ʌnkənˈsɜːrn/

Unconcern

漠不关心
Meaning
lack of worry or interest; indifference
Example
She showed complete unconcern about the criticism.
她对批评表现出了完全的漠不关心。
C1 adjective /ˌʌnfɔːrθˈkʌmɪŋ/

unforthcoming

不合作的
Meaning
Not willing to talk or provide information; uncooperative.
Example
The witness was unforthcoming about what he had seen.
证人对于他所见的情况不合作。
B2 adjective /ʌnˈɪndʒərd/

uninjured

未受伤
Meaning
Without injury; not physically harmed.
Example
All the passengers were rescued uninjured.
所有乘客都没有受伤并被救援。
B2 adjective /ʌnˈkɒmən/

uncommon

不常见
Meaning
rare, unusual, or remarkable
Example
It is uncommon to see snow in this region.
在这个地区看到雪是不常见的。
B2 adjective /ʌnˈkɒn.ʃəs/

Unconscious

昏迷; 无意识
Meaning
not awake and aware of one's surroundings; done or existing without one realizing
Example
The patient was unconscious for several hours after the surgery.
病人在手术后昏迷了几个小时。
B2 adjective /ʌnˈiːvən/

Uneven

不平; 粗糙
Meaning
not level or smooth; not regular or consistent
Example
The road was uneven and full of potholes.
那条路不平，充满了坑洞。
C2 adjective /ʌnˈfeɪnd/

unfeigned

真诚
Meaning
genuine; not pretended or insincere
Example
She expressed unfeigned joy at her friend's success.
她在朋友的成功上表达了真诚的喜悦。
B1 adjective /ʌnˈmærid/

unmarried

未婚
Meaning
Not married; single.
Example
He is thirty-five and still unmarried.
他三十五岁，仍然未婚。
C1 verb /ʌnˈsɛtl/

unsettle

扰乱
Meaning
To disturb or make someone feel anxious or uneasy.
Example
The sudden news unsettled the entire community.
突如其来的消息让整个社区感到不安。
B1 adjective /ˈjuːnɪfɔːrm/

Uniform

制服
Meaning
consistent; identical; standardized
Example
All students must wear a uniform to school.
所有学生必须穿制服上学。
B2 adverb /ʌnˈnesəserəli/

Unnecessarily

不必要地
Meaning
to a greater extent than is needed; without necessity
Example
Don't worry unnecessarily about the exam.
不要为考试不必要地担心。
B2 adjective /ʌnprəˈdʌk.tɪv/

Unproductive

无效的; 不起作用的
Meaning
not achieving much; not producing good results
Example
The meeting was unproductive and wasted everyone's time.
会议是无效的，浪费了大家的时间。
B2 adjective /ˌʌndərˈlaɪɪŋ/

underlying

基本的
Meaning
basic or hidden but important; forming the foundation of something
Example
The underlying reason for the conflict was never addressed.
冲突的根本原因从未得到解决。
B2 adjective /ʌnˈbæləns/

Unbalanced

不平衡的; 不稳定的
Meaning
not balanced; lacking stability or equilibrium; mentally unstable
Example
The unbalanced table kept wobbling.
不平衡的桌子摇晃着。
C1 adjective /ˌjuːtɪlɪˈtɛəriən/

utilitarian

Meaning
Designed to be useful or practical rather than attractive; relating to the doctrine that actions are right if they are useful or for the benefit of a majority.
Example
The building had a simple utilitarian design.
A1 interjection /ʌ/

uh

呃
Meaning
a sound people make when they hesitate or are unsure what to say next.
Example
Uh, I’m not sure if that’s the right answer.
呃，我不确定这是不是正确的答案。
C2 noun /ˈʌp.wel.ɪŋ/

upwelling

上升流
Meaning
An oceanographic phenomenon that involves wind-driven motion of dense, cooler, and nutrient-rich water towards the ocean surface.
Example
Upwelling brings nutrients to the ocean surface.
上升流将营养物质带到海洋表面。
B2 adjective /ʌnˌkənˈfɜːmd/

Unconfirmed

未确认; 未验证;
Meaning
not confirmed as true or definite; not verified or substantiated
Example
The report remains unconfirmed until we receive official verification.
报告在我们收到官方验证之前保持未确认状态。
C2 noun /ˈʌn.dɚˌstɔː.ri/

understory

下层植被
Meaning
The layer of vegetation beneath the main canopy of a forest.
Example
The understory of a rainforest is home to small mammals and insects.
雨林的下层植被是小型哺乳动物和昆虫的家园。