1NEEDsomething that is necessary is what you need to have or need to do 必要的,必需的,必不可少的 → essential
The booklet provides all the necessary information about the college.
这本小册子提供了关于那所学院的所有必需信息。
No further changes were considered necessary.
没有必要作出进一步的改变。
absolutely/really necessary
The police are advising motorists to travel only if their journey is absolutely necessary.
警方建议驾驶员如非万不得已不要驾车出行。
it is necessary (for somebody) to do something
It’s not necessary to wear a tie.
不一定要打领带。
The doctor says it may be necessary for me to have an operation.
医生说我可能需要做手术。
make it necessary (for somebody) to do something
Falling profits made it necessary to restructure the business.
利润下滑使得公司必须重组。
necessary for (doing) something
A good diet is necessary for maintaining a healthy body.
想保持身体健康,合理饮食必不可少。
if/when/where necessary
I’ll stay up all night, if necessary, to get it finished.
如有必要,我会熬个通宵把这事做完。
Register
In everyday English, instead of saying it is necessary for somebody to do something, people usually say that someone has to do something: 在日常英语中,人们一般不说it is necessary for sb to do sth,而是说someone has to do sth
The doctor says it might be necessary for me to have an operation. → The doctor says I might have to have an operation. 医生说我可能必须得做手术。
2necessary connection/consequence etcMUSTa connection, result etc that must exist and cannot be avoided 必然的联系/结果等
The closure of the factory was a necessary consequence of increased competition from abroad.
工厂倒闭是来自国外的竞争加剧的必然结果。
Examples from the Corpus
necessary connection/consequence etc• Normativepositivismasserts what legal positivists deny, namely that there is a necessary connection between law and positivemorality.• Men. come and go in their lives, but there is no necessary connection between motherhood and marriage.• It is further easy to see that there is no necessary connection between subsidy-free prices and Ramsey-optional prices.• The difficulty is finding any necessary connection between two cases.• That stratification would occur as a necessary consequence of the alienation of labour.• These are, however, necessary consequences of the division of labour and the consequentrole of trust in social relationships.• In neither ease was the omission a necessary consequence of the intellectualstance of the two schools.• Neither is upwardmobility, rising income or independence a necessary consequence of their diligence.
3a necessary evilMUSTsomething bad or unpleasant that you have to accept in order to achieve what you want 〔为实现目的不得不接受的〕不得已的事,难免的坏事
Mr Hurst regarded work as a necessary evil.
赫斯特先生把工作看成是迫不得已的事情。
Examples from the Corpus
a necessary evil• I, for one, consider yard work to be a necessary evil.• Mr Waldegrave's shambolicperformance in the pressconference was a necessary evil.• We do not look at government as a necessary evil.• It may be a necessary evil, but it is surely an evil.• However, the authors, like most others then and now, saw those shortcomings as a necessary evil in maintaining control.• They're a necessary evil, like the woman who sawed off all my lovelyhair.• Lawyers are a necessary evil that I try to use as little as possible due to their cost.• Bureaucracy was also a necessary evil to cope with the ravages of war.• They viewed such methods as a necessary evil, unavoidable yet somehow beneath their dignity.
THESAURUS
necessary used to describe something that you need to have or do 必需的,必要的
Make sure you bring the necessary documents with you.
一定要带好所需的文件。
It may be necessary for you to have a small operation.
你可能需要做个小手术。
essential very important and necessary, especially in order to be healthy, successful etc 〔尤为健康或取得成功〕非常必要的,必不可少的
Vitamins are essential for healthy growth.
维生素对于健康成长必不可少。
The tourist industry is an essential part of the Spanish economy.
旅游业是西班牙的经济支柱。
vital extremely important and necessary, especially in order to avoidserious problems 〔尤为避免重大问题〕必不可少的,非常重要的
A vital piece of equipment on the spacecraft had stopped operating.
航天器上的一个重要设备停止了运转。
It is vital that the aid is sent immediately.
必须马上派出救援。
compulsory if something is compulsory, you must do it because of a rule or law 〔根据法律或法规规定〕必须做的,强制性的
Maths and Science are compulsory subjects.
数学和科学是必修课。
All new staff undergo a compulsory training course.
所有新员工都必须参加一个培训课程。
obligatory if something is obligatory, you must do it because of a rule or law. Obligatory is more formal than compulsory 〔根据法律或法规规定〕必须做到的,义务的〔obligatory 比compulsory正式〕
The use of seatbelts is obligatory.
系安全带是强制性的。
Safety regulations have made it obligatory for all competitors to wear fist protectors.
安全条例规定所有参赛者都必须戴拳套。
mandatory if something is mandatory, you must do it because it is the law. Mandatory is more formal than compulsory and sounds stronger 依法必须做的,强制性的〔mandatory比compulsory正式,语气也更加强烈〕
School attendance is mandatory.
上课出勤是必须的。
a prisoner serving a mandatory life sentence
依法被终身监禁的犯人
requisite /ˈrekwəzət/ formal [usually before noun] the requisite things are the ones that you need to have in order to do something 〔为了做某事〕需要的,必要的,必备的
The other candidates lacked the requisite skills.
其他求职者缺少必要的技能。
nthe requisite evidence needed for a successful prosecution
Examples from the Corpus
necessary• She explainedwhy change was necessary.• Add a second layer if necessary.• Jennie told Katharine to be aware of this and to correct any fault as necessary.• Computers are as necessary as textbooks in schools.• They also make any necessarycriticisms and suggestions more easily acceptable when they are offered.• He produced the necessarydocuments and handed them to her.• Fats in our diet are necessary for both heat and energy.• The doctor says it may be necessary for me to have an operation.• This was clearly necessary for their analysis since it allowed them to aggregate data over different drivers.• Much doubling, therefore, is necessary in the tutti.• It will be necessary to close the pool while the repairs take place.• On his eighteenth birthday, his parents had believed it necessary to commit the act that would decisively save their only child.• But take another step back and it is no longer necessary to preserve the species.• If necessary, we will have to employ some outside people to finish the job.