necessary
adj
noun
ˈnesɪəsəri adj
1 something that is necessary is what you need to have or need to do 必要的，必需的，必不可少的;
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要信息。
No further changes were considered necessary.
没有必要作出进一步变动。
absolutely/really necessary
The police are advising motorists to travel only if their journey is absolutely necessary.
警方建议汽车驾驶员只在不得已的情况下才驾车出行。
it is necessary (for sb) to do sth
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 sb) to do sth
Falling profits made it necessary to restructure the business.
利润下滑使公司有必要重组。
necessary for (doing) sth
A good diet is necessary for maintaining a healthy body.
想保持身体健康，合理的饮食必不可少。
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儿做完。
2
necessary connection/consequence etc
a 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.
工厂倒闭是国外日趋激烈的竞争所导致的必然结果。
3
a necessary evil
something 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一件不得已的事情。
noun
4
necessaries
things such as food or basic clothes that you need in order to live （生活）必需品 plural 复数
5
do the necessary
to do what is necessary [英，口] 做必要的事 BrE spoken
Leave it to me – I’ll do the necessary.
交给我吧，我会把该办的事都办好的。