常用结构有：
be in need of ... 需要…
feel the necessity of ... 感到有…的必要
it is necessary / essential + (for ...)to V 必须…
make it necessary / unnecessary + to V 使…成为必要／不必要
make necessary / unnecessary + NP 需要／不需要
must / should + V 必须…
need / require / necessitate + NP 需要／要求／使成为必需(必要)
obviate / dispense with / do away with the need for ...
消除了对…的需要，无需…
there is no need / necessity of / for / to V 没有…的必要，无需…
Some cities are in urgent need of new water supplies .
有些城市急需新的供水水源。
To understand how semiconductors work it is necessary to review briefly the structure of matter．
要了解半导体器件如何工作，必须先粗略地了解一下物质的结构。
It is essential for the process to be carried out quickly .
这一过程必须很快地进行。
This type of engine needs / requires very little maintenance .
这种发动机需要的维修保养工作很少。
The production of this new model will necessitate complete retooling of factory .
生产这种新的型号(汽车)将需要对工厂进行重新装备。
Half-life is the time required for a radioactive substance to be reduced to 50 percent of its original radioactivity .
半衰期是放射性物质的放射性被降到原来的一半所需的时间。
A large area of heating surface is necessary to produce the required weight of steam.
要生产所需重量的蒸汽，需要有大面积的受热面。
The use of plastic pipes makes unnecessary / obviates the need for protection against corrosion．
使用塑料管子就不必考虑防腐蚀的问题了。
A force of attraction then acts between the two poles , making it necessary to exert a force to separate them .
这时两极之间有一力作用，因而需要施加一个力才能把两个极分开。
The bearings must be lubricated．
轴承需要加以润滑。
To ensure freedom from distortion , it is necessary for the metal bar to be cooled slowly .
为了保证不发生变形，金属棒必须慢慢冷却。
There is no need for any readjustment after operation .
开动后无需再作调整。
责任编辑：admin
上一篇：“过量”等的科技英语表示法及翻译例句
下一篇：科技德语中“潜在”因果关系的翻译处理
微信公众号搜索“译员”关注我们，每天为您推送翻译理论和技巧，外语学习及翻译招聘信息。