compulsory
英 [kəmˈpʌlsəri] 美 [kəmˈpʌlsəri]
（因法律或规则而）必须做的，强制的，强迫的
- Swimming was compulsory at my school.
在我们学校，游泳是必修课。 - The law made wearing seat belts in cars compulsory.
坐车系安全带是法律强制规定的。 - compulsory education/schooling
义务教育
essence
英 [ˈesns] 美 [ˈesns]
本质、实质、精髓
- 他的画描绘出了法国的神韵。但他到伦敦小画廊兜售自己的画作，结果却以大败告终。
His paintings captured the essence of France. But his attempts to peddle his paintings around London's tiny gallery scene ended in a fiasco. - 由于时间至关重要，他强制性地推行了改革。
He railroaded the reforms through because time was of the essence.
延伸阅读：小词详解 | essence
entail
英 [ɪnˈteɪl] 美 [ɪnˈteɪl]
牵涉、需要、使必要
- The job entails a lot of hard work.
这工作需要十分艰苦的努力。 - The girls learn exactly what is entailed in caring for a newborn baby.
姑娘们学的正是怎样照看新生儿。 - It will entail driving a long distance every day.
这意味着每天都要长途开车。
gratuitous
英 [ɡrəˈtjuːɪtəs] 美 [ɡrəˈtuːɪtəs]
[贬义]无正当理由（或目的）的；无谓的
- A lot of viewers complained that there was too much gratuitous sex and violence in the film.
很多观众抱怨说影片中有太多无谓的色情和暴力镜头。 - There's too much crime and gratuitous violence on TV.
电视里充斥着犯罪和无端的暴力。
imperative
英 [ɪmˈperətɪv] 美 [ɪmˈperətɪv]
重要紧急的、迫切的、急需处理的
- The president said it was imperative that the release of all hostages be secured.
总统说当前要务是确保所有人质都获释。 - It's imperative to act now before the problem gets really serious.
必须现在就采取行动，而不是等到问题变得难以收拾。
incumbent
英 [ɪnˈkʌmbənt] 美 [ɪnˈkʌmbənt]
有责任、必须履行
- She felt it incumbent upon/on her to raise the subject at their meeting.
她感到她有义务在他们的会上提出这个问题。 - It is incumbent upon all of us to make an extra effort.
我们所有人都必须加倍努力。
indispensable（反义词：dispensable）
英 [ˌɪndɪˈspensəbl] 美 [ˌɪndɪˈspensəbl]
不可或缺的、必不可少的
- 一本好词典是学习一门外语必不可少的。
A good dictionary is indispensable for learning a foreign language. - 他们将印度视为其与中国的竞争中不可或缺的帮凶。
They see India as an indispensable accomplice in their rivalry with China.
（拓展学习：本周《经济学人》封面用这个词形容美印关系）
necessitate
英 [nəˈsesɪteɪt] 美 [nəˈsesɪteɪt]
[正式]使成为必要
- Recent financial scandals have necessitated changes in parliamentary procedures.
最近的金融丑闻使得议会程序必须改革。 - Increased traffic necessitated widening the road.
交通量增大，这就需要拓宽道路。 - His new job necessitated him/his getting up at six.
新工作使他不得不六点钟起床。
oblige
英 [əˈblaɪdʒ] 美 [əˈblaɪdʒ]
（以法律、义务等）强迫、迫使
- The law obliges companies to pay decent wages to their employees.
法律强制公司向其雇员支付适当的工资。 - The law does not obligate sellers to accept the highest offer.
法律没有强制卖主必须接受最高的出价。 - I felt obliged to ask them to dinner.
我不得不请他们吃饭。 - He suffered a serious injury that obliged him to give up work.
他受伤严重，不得已只好放弃工作。
obviate
英 [ˈɒbvieɪt] 美 [ˈɑːbvieɪt]
消除、排除、打消
- A peaceful solution would obviate the need to send a UN military force.
如果能和平解决就没有必要派遣联合国维和部队了。 - This new evidence obviates the need for any further enquiries.
这项新证据排除了继续调查的必要。
prerequisite
英 [ˌpriːˈrekwəzɪt] 美 [ˌpriːˈrekwəzɪt]
先决条件、前提、必备条件
- A degree is an essential prerequisite for employment at this level.
学位是做这级工作必备的先决条件。 - Good self-esteem is a prerequisite for a happy life.
良好的自尊是幸福生活的前提。 - Party membership was an essential prerequisite of a successful career.
成为党员是事业有成必不可少的先决条件。
pressing
英 [ˈpresɪŋ] 美 [ˈpresɪŋ]
紧急的、急迫的
- a pressing need for housing
对住房的迫切需求 - a pressing issue
紧迫的问题 - The most pressing question is what do we do next?
最迫切的问题是接下来我们要做什么？
superfluous
英 [suːˈpɜːfluəs] 美 [suːˈpɜːrfluəs]
过剩的、过多的、多余的
- The report was marred by a mass of superfluous detail.
这篇报告坏就坏在里面细枝末节的东西太多。 - She gave him a look that made words superfluous.
她看了他一眼，这已表明一切，无须多言了。 - My presence at the afternoon's proceedings was superfluous.
我去参加下午的活动是多此一举。
