unfaltering
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C1 adjective /ʌnˈfɔːltərɪŋ/

unfaltering

坚定不移
Meaning
Steady and resolute; not weakening or hesitating
Example
She continued with unfaltering determination.
她以坚定不移的决心继续前进。
B2 adjective /ʌnˈfeɪ.vər.ə.bəl/

Unfavourable

不利的; 逆境的
Meaning
not helpful or advantageous; adverse
Example
The weather conditions were unfavourable for our outdoor event.
恶劣的天气条件不利于我们的户外活动。
B2 adjective /ʌnˈfeɪθ.fəl/

Unfaithful

不忠诚
Meaning
not loyal or true to a spouse, partner, or commitment
Example
He was unfaithful to his wife for many years.
他对妻子不忠诚多年。
C2 adjective /ʌnˈmɪtɪɡeɪtɪd/

unmitigated

完全
Meaning
absolute; not lessened or moderated
Example
The meeting was an unmitigated disaster.
会议是一次完全的灾难。
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 verb /ʌnˈkaʊtʃ/

uncouch

从沙发上移开（罕见用法）
Meaning
to remove from a couch or to release from being laid down (rare/archaic usage)
Example
The surgeon attempted to uncouch the cataract.
外科医生试图去除白内障。
A2 adjective /ˈʌɡ.li/

Ugly

丑陋的; 可憎的; 可怕的
Meaning
unpleasant or repulsive in appearance; morally reprehensible
Example
The old building looked ugly after years of neglect.
这座老建筑在多年疏忽之后看起来很丑。
B2 verb /ˈjuːtɪlaɪz/

utilize

利用
Meaning
to make practical or effective use of something
Example
The company aims to utilize solar energy for production.
公司旨在利用太阳能进行生产。
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 /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。
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。
C1 noun /ˈʌlsər/

ulcer

Meaning
a sore on the skin or a mucous membrane that does not heal easily
Example
The doctor prescribed medicine to treat the stomach ulcer.
B1 adjective /ʌnˈedjʊkeɪtɪd/

Uneducated

未受教育的; 文盲
Meaning
lacking education; not having received formal schooling or training
Example
Many uneducated workers struggle to find well-paying jobs.
许多未受教育的工人很难找到薪水高的工作。
C1 adjective ʌnˈtʃɑːtɪd

uncharted

未标记
Meaning
Not mapped or surveyed; unknown or unexplored.
Example
The mission aimed to explore uncharted areas of the planet.
该任务旨在探索星球上未标记的区域。
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 noun /ʌnˈrest/

Unrest

不安；动荡；社会或政治动乱
Meaning
a state of dissatisfaction and disturbance; social or political disorder
Example
The economic crisis led to widespread social unrest.
经济危机导致了广泛的社会不安。
B2 noun /ʌnəˈbɪləti/

unability

无能
Meaning
the state of being unable to do something; incapacity
Example
His unability to solve the problem caused delays in the project.
他解决问题的无能导致了项目的延误。
C2 adjective /ʌnˈʌtərəbl/

unutterable

难以言喻
Meaning
Too great, intense, or awful to be expressed or described in words.
Example
She was filled with unutterable joy at the news of her success.
她听到成功的消息时充满了难以形容的喜悦。
A2 adjective /ˈjuːʒəl/

usual

常见
Meaning
habitually or typically occurring or done
Example
It’s our usual meeting spot.
这是我们常见的会议地点。
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。
B2 verb /ʌnˈveɪl/

unveil

揭示
Meaning
to reveal or disclose something, especially in a formal manner
Example
The company will unveil a new product next week.
公司将在下周揭示一款新产品。
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 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。
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。
C1 adjective /ˌʌnəkˈnɒlɪdʒd/

unacknowledged

未承认的
Meaning
Not recognized, admitted, or accepted; ignored or unnoticed
Example
Her contributions to the project went unacknowledged.
她对项目的贡献未被承认。
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。
B1 adjective ʌnˈplænd

unplanned

未计划的
Meaning
Not planned or arranged in advance; happening spontaneously without preparation.
Example
Unplanned urbanization contributes to environmental issues.
无计划的城市化会加剧环境问题。
B2 adjective /ʌnˈwɪl.ɪŋ/

Unwilling

不愿意的; 不情愿的;
Meaning
not ready to do something; reluctant; not wanting to do
Example
He was unwilling to share his secret with anyone.
他不愿意与任何人分享他的秘密。
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 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。
C1 adjective /ˌʌnsəˈfɪstɪˌkeɪtɪd/

unsophisticated

不复杂
Meaning
Lacking worldly experience, refinement, or complexity.
Example
The villagers led an unsophisticated but happy life.
村民过着简单而幸福的生活。
B2 adverb /ʌnˈkɒnʃəsli/

unconsciously

无意识地
Meaning
without being aware of one's actions or surroundings
Example
She unconsciously tapped her foot to the rhythm of the music.
她无意识地跟着音乐的节奏轻轻跺脚。
B1 adjective /ʌnˈjuzd/

Unused

未使用的; 没有被使用
Meaning
not being used; not having been used before
Example
There are many unused rooms in this old mansion.
这个古老的豪宅里有许多未使用的房间。
C1 adjective /ˌʌnəbˈtruːsɪv/

unobtrusive

不引人注目
Meaning
not attracting attention; blending in without causing notice
Example
The security cameras are designed to be unobtrusive.
安全摄像头被设计成不引人注目。
B1 noun /ˌʌnɪmˈplɔɪmənt/

Unemployment

失业
Meaning
the state of being unemployed; lack of paid work
Example
The unemployment rate has increased significantly this year.
今年失业率显著上升。
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。
B2 adjective /ʌnˈendɪŋ/

Unending

无尽的
Meaning
continuing forever; without end
Example
The unending rain made the day feel gloomy.
无尽的雨让这一天显得阴沉。
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。
C1 verb /ʌnˈmɑːsk/

unmask

揭露；暴露真相
Meaning
to remove a mask or covering; to reveal the true identity, nature, or intentions of someone or something
Example
The investigation helped unmask the real culprit behind the crime.
调查帮助揭露了犯罪背后的真正罪犯。
C1 noun /ˌʌnprɪˈdɪktəˌbɪləti/

unpredictability

不可预测性
Meaning
The quality of being impossible to predict or anticipate.
Example
The unpredictability of the weather made the trip uncertain.
天气的不可预测性使得旅行充满不确定性。
B2 noun /juːˈtɪl.ə.ti/

Utility

效用; 益处; 公共服务
Meaning
the state of being useful, profitable, or beneficial; a public service
Example
The utility of solar panels increases with rising electricity costs.
随着电费上涨，太阳能板的效用也在增加。
C2 adjective /ˌʌnprəˈpɪʃəs/

unpropitious

不利
Meaning
Not giving or indicating a good chance of success; unfavorable.
Example
The team began their journey under unpropitious weather conditions.
团队在不利的天气条件下开始了他们的旅程。
B1 verb /ʌnˈlɒk/

unlock

解锁
Meaning
to open something that is locked; to make something accessible or available
Example
She used the key to unlock the door.
她用钥匙解锁了门。
B2 adjective /ʌnˈɑːrmd/

unarmed

手无寸铁
Meaning
Not equipped with or carrying weapons
Example
The police found the suspect unarmed during the search.
警察在搜查过程中发现嫌疑人没有武器。
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。
C1 adjective /ˌʌnˈpɑr.də.nə.bəl/

Unpardonable

不可宽恕的
Meaning
too bad to be forgiven; inexcusable
Example
His betrayal of trust was an unpardonable offense.
他的背叛是不可原谅的罪行。
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。
B2 adverb juːˈnæn.ɪ.məs.li

unanimously

一致通过
Meaning
With the agreement of all people involved; without opposition.
Example
The proposal was unanimously accepted.
提案得到了全体一致通过。
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。
B2 noun /ˌʌnəˌveɪləˈbɪləti/

unavailability

不可用性
Meaning
The state of being not available or not accessible.
Example
The unavailability of the manager caused a delay in the project.
经理的不可用性导致了项目的延误。
C1 adjective /ʌnˈmɒdɪfaɪd/

unmodified

未修改的
Meaning
not changed from its original form or state
Example
The data was used in its unmodified form for analysis.
这些数据以未修改的形式用于分析。
C2 adjective /juːˈbɪkwɪtəs/

ubiquitious

无处不在
Meaning
Present, appearing, or found everywhere.
Example
Smartphones have become ubiquitous in modern society.
智能手机已经在现代社会中无处不在。
C2 noun /ˈʌŋɡwənt/

unguent

药膏
Meaning
A soothing or healing ointment applied to the skin.
Example
The doctor applied an unguent to heal the burn.
医生涂抹了药膏来治愈烧伤。
C1 adjective /ʌnˈvaɪəbl/

unviable

不可行的
Meaning
Not capable of working successfully; not feasible or practical.
Example
The project was deemed unviable due to high costs.
由于高昂的成本，该项目被认为不可行。
C2 adjective /ˌʌnəˈʃʊəd/

unassured

不确定的
Meaning
Lacking confidence or certainty.
Example
She gave an unassured answer during the interview.
她在面试中给出了一个不确定的答案。
C1 noun /ˈʌp.tɜːn/

upturn

改善
Meaning
An improvement or upward trend in a situation, especially in business or economy.
Example
The company experienced an upturn in sales last quarter.
该公司在上个季度销售情况有所改善。
C1 adjective /ʌnˈɒnəd/

unhonoured

未受尊敬的
Meaning
not respected or given the recognition that is deserved; treated without honor
Example
He felt unhonoured after his years of service were ignored.
他的多年服务被忽视后，他感到自己未受尊敬。
B2 adverb /ˈɜːrdʒəntli/

urgently

紧急地
Meaning
in a way that requires immediate attention or action
Example
The patient urgently needs medical attention.
病人紧急地需要医疗救助。
C1 adjective /ʌnˈsɜːrvɪsəbəl/

Unserviceable

无法使用的; 有缺陷的
Meaning
not in working order; unable to be used; defective
Example
The old computer became unserviceable after the system crash.
那台旧电脑在系统崩溃后变得无法使用。
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。
C1 adjective /ʌnˈhoʊli/

Unholy

亵渎的; 罪恶的; 亵渎的
Meaning
wicked; sinful; profane
Example
The unholy alliance between the two companies caused public outrage.
这两家公司之间的不圣洁联盟引发了公众愤怒。
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。
C2 verb /juˈzɜrp/

usurp

篡位
Meaning
to take someone's position of power illegally or by force
Example
The general tried to usurp the king's throne.
将军试图篡夺国王的王位。
C2 verb /ˌʌn.dɪˈsiːv/

undeceive

解惑
Meaning
To free someone from a misconception or false belief.
Example
She tried to undeceive him about the false rumors.
她试图让他摆脱这些错误的谣言。
C2 adjective /ˌʌnrɪˈmɪtɪŋ/

unremitting

不断的
Meaning
Never relaxing or stopping; persistent.
Example
Her unremitting efforts finally paid off.
她不懈的努力终于得到了回报。
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。
B2 noun /ʌnˈkaɪndnəs/

unkindness

不友善
Meaning
lack of kindness; cruel or inconsiderate behavior
Example
His unkindness hurt her feelings deeply.
他的不友善深深伤害了她的感情。
C2 adjective /ˌʌnɪkˈsɛpʃənəbl/

unexceptionable

无可指摘
Meaning
Not open to objection; acceptable and unobjectionable
Example
His behavior was unexceptionable throughout the event.
他的行为在整个事件中都是无可指摘的。
C1 adjective /ʌnˈmænɪdʒəbəl/

Unmanageable

无法控制的; 失控
Meaning
difficult or impossible to control or handle
Example
The large class became unmanageable without proper supervision.
没有适当的监督，班级变得无法控制。
A2 adjective /ʌnˈhel.θi/

Unhealthy

不健康的; 有害的
Meaning
harmful to health; not in good health; detrimental to well-being
Example
Eating too much fast food is unhealthy for your body.
吃太多快餐对你的身体不健康。
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 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。
C1 noun ˈʌp.raɪ.zɪŋ

uprising

起义
Meaning
An act of resistance or rebellion; a revolt against an authority or government.
Example
The uprising marked the beginning of the revolution.
起义标志着革命的开始。
A1 verb /juːz/

use

使用
Meaning
to employ something for a purpose; to take advantage of
Example
I use my computer for work and entertainment.
我用我的计算机来工作和娱乐。
C2 noun /ˈʌm.brə/

Umbra

完全的阴影，太阳黑子的黑暗中心
Meaning
the fully shaded inner region of a shadow cast by an opaque object; the dark center of a sunspot
Example
During the eclipse, we stood in the moon's umbra.
在日食期间，我们站在月亮的本影中。
C2 noun /ˈʌŋkʃən/

unction

涂抹
Meaning
The act of anointing as part of a religious or ceremonial ritual; excessive or insincere flattery.
Example
The priest performed the holy unction with solemnity.
牧师庄重地进行了神圣的涂抹仪式。
B2 adjective /ʌnˈiːkwəl/

Unequal

不平等; 不公正;
Meaning
not the same in quantity, size, or value; not fair or just
Example
The distribution of wealth is unequal in many countries.
财富的分配在许多国家是不平等的。
B2 verb /ˌʌndərˈskɔːr/

underscore

强调
Meaning
to emphasize or highlight something
Example
The incident underscored the need for better safety measures.
这起事件突显了更好安全措施的必要性。
C1 verb /ˌʌn.dəˈtʃɑːrdʒ/

undercharge

收取较少费用
Meaning
To charge less than the correct or fair amount.
Example
The shopkeeper accidentally undercharged me for the groceries.
店主不小心少收了我购买食品的钱。
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。
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.
B2 noun /ʌnˈsɜːrtənti/

Uncertainty

不确定性; 怀疑或缺乏确信
Meaning
the state of being uncertain; doubt or lack of sureness
Example
The uncertainty about the weather delayed our trip.
关于天气的不确定性延迟了我们的旅行。
B2 adjective /ʌnˈhɛlpfəl/

unhelpful

没有帮助的
Meaning
not providing help or support; making a situation harder rather than easier
Example
His unhelpful attitude slowed down the entire project.
他没有帮助的态度拖慢了整个项目。
B2 adjective /ʌnˈstɛdi/

unsteady

不稳定的
Meaning
not firm or stable; likely to change or fail
Example
She felt unsteady on her feet after the long journey.
长途旅行后，她感到站立不稳。
B1 adjective /ʌnˈjuː.ʒu.əl/

Unusual

不寻常; 奇怪;
Meaning
not typical; strange; different from what is normal
Example
She wore an unusual dress to the party.
她穿了一件不寻常的衣服去参加派对。
C2 adjective /ʌnˈkɒnʃənəbl/

unconscionable

不合理的
Meaning
shockingly unfair or unreasonable
Example
The company made unconscionable profits from the crisis.
公司从危机中获得了不合理的利润。
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。
C2 adjective /ʌnˈɡeɪnli/

ungainly

笨拙
Meaning
Awkward, clumsy, or lacking grace in movement or appearance.
Example
The tall boy moved in an ungainly manner.
那个高个男孩以笨拙的方式走动。
C2 adjective /ʌnˈtræməld/

untrammeled

无限自由
Meaning
Not restricted or hampered; free and unrestricted.
Example
She enjoyed untrammeled freedom in her new life abroad.
她在国外的新生活中享受着无限自由。
B1 adjective /ˌʌnˈpeɪd/

Unpaid

未支付的; 无薪的
Meaning
not paid for; without payment or salary
Example
She worked as an unpaid intern for six months.
她作为一名无薪实习生工作了六个月。
B1 adverb /ˌʌpsaɪd ˈdaʊn/

Upside-down

倒过来
Meaning
with the upper part at the bottom; in or into a reversed position
Example
The picture was hanging upside-down on the wall.
图片倒挂在墙上。
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。
B2 adjective /ʌnˈhɜːrt/

unhurt

毫发无损
Meaning
Not injured or harmed.
Example
She walked away from the accident unhurt.
她在事故中毫发无损。
B1 adjective /juːˈnaɪtɪd/

United

联合的; 一致的; 团结的
Meaning
joined together for a common purpose; in agreement
Example
The team was united in their goal to win.
团队在他们的目标上达成了统一。
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。
C1 adjective /ˈʌndərhænd/

underhand

阴险
Meaning
done secretly and dishonestly; deceitful
Example
The politician was accused of using underhand tactics to win the election.
那位政治家被指控使用阴险的手段赢得选举。
B2 adjective /ˈʌl.tɪ.mət/

Ultimate

最终的; 极致的; 终极的
Meaning
being the best or most extreme example of its kind; final; last
Example
This is the ultimate test of your skills.
这是你技能的终极考验。
B2 adjective /ˌʌnˈnoʊ.tɪst/

Unnoticed

未被注意到; 被忽视
Meaning
not seen or observed; ignored
Example
His hard work went unnoticed by his manager.
他的辛勤工作没有被经理注意到。
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。
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 /ˈjuːnɪsən/

unison

齐声
Meaning
Simultaneous performance or utterance of action or speech.
Example
The choir sang in unison.
合唱团齐声唱歌。
C2 adjective /ˈʌndjʊləs/

undulous

波浪形的
Meaning
Having a wavy surface or form.
Example
The artist painted the undulous sea at sunset.
艺术家在日落时画了波浪形的海洋。
C1 adjective /ʌnˈsɪvəl/

Uncivil

不文明的; 粗鲁的;
Meaning
not polite or courteous; rude and discourteous in behavior
Example
His uncivil remarks during the meeting offended everyone present.
他在会议上的不文明言论冒犯了在场的每一个人。
B2 adjective /ʌnˈtʃeɪndʒɪŋ/

unchanging

不变的
Meaning
remaining the same over time; not changing
Example
Her love for her family was unchanging throughout the years.
她对家人的爱多年来始终不变。
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。
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。
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。
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。
C1 adjective /ʌnˈkʌltʃəd/

Uncultured

不文明的; 无文化的
Meaning
lacking good manners, refinement, or education; uncivilized
Example
His uncultured behavior embarrassed everyone at the dinner party.
他在晚宴上的不文明行为让所有人感到尴尬。
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 /ˌjuːnɪˈvɜːrsəl/

Universal

普遍的
Meaning
applicable to all cases; existing everywhere
Example
Music is a universal language that everyone understands.
音乐是一种普遍的语言，人人都能理解。
B2 noun /ˌʌndəˈɡrædʒuət/

undergraduate

本科生
Meaning
a student who has not yet earned a bachelor's degree
Example
She is an undergraduate studying computer science.
她是一个学习计算机科学的本科生。
C2 adjective /ˌʌltrəˈmɒnteɪn/

ultramontane

教皇支持者
Meaning
beyond the mountains, especially referring to support for the Pope over local church authority
Example
The debate highlighted the ultramontane position in church politics.
辩论突出了教会政治中超山的立场。
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。
C2 adjective /ʌnˈflɛdʒd/

unfledged

未经训练的
Meaning
Inexperienced, immature, or not fully developed.
Example
The unfledged writer struggled to complete his first novel.
这个未经训练的作家难以完成他的第一本小说。
B2 adjective /ˌʌnprɪˈdɪktəbəl/

unpredictable

不可预测的
Meaning
not able to be predicted; changing suddenly and unexpectedly
Example
The weather in this region is highly unpredictable.
这个地区的天气非常不可预测。
B2 adverb /ʌnˈkaɪndli/

unkindly

残忍地
Meaning
in a cruel, harsh, or unsympathetic manner
Example
She spoke unkindly about her colleague during the meeting.
她在会议期间残忍地谈论了她的同事。
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。
C1 adjective /ʌlˈtɪəriər/

ulterior

隐藏的动机
Meaning
hidden or secret, often with a selfish motive
Example
He invited her with an ulterior motive.
他带着隐藏的动机邀请了她。
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。
A2 noun /ˈʌndərweər/

underwear

内衣
Meaning
Clothing worn beneath outer clothes, typically next to the skin.
Example
He bought new underwear for the trip.
他为旅行买了新的内衣。