分译：介词短语作定语时，总是是定语从句的一种简略形式。介词短语作状语时，有时是状语从句的简略形式。有的介词短语还是并列句的简略形式。因此汉译时，有些可以拆句分译。
①译成并列分句。
The porous wall acts as a kind of seine for separating molecules.多孔壁有哪些用途就象一把筛子，它把不同水平的分子分开。
②译成让步分句。
With all its disadvantages this design is considered to be one of the best.这个设计尽管有种种缺点，仍被觉得最好设计之一。
③译成真实或虚拟条件分句。
Mans warm blood makes it difficult for him to live long in the sea without some kind warmth.人的血液是热的，假如得不到肯定的热量，人就很难长期在海水中生活。
④译成缘由分句。
We cannot see it clearly for the fog.因为有雾，大家看不清它。
The machine is working none the worse for its long service.
这部机器并不因用的时间长而性能变差了。
⑤译成目的分句。
This body of knowledge is customarily divided for convenience of study into the classifications： mechanics， heat， light， electricity and sound.。为了便于研究起见，一般将这门学科分为力学、热学、光学、电学和声学。
不译：不译或省略翻译是在确切表达原文内容的首要条件下使译文简练，合乎汉语规范，决不是任意省略某些介词。
①表示时间或地址的英语介词，译成汉语如出目前句首，大都不译。如：
There are four seasons in a year. 一年有四季。
Many water power stations have been built in the country.国内已建成很多水电站。
②有的介词如for，from，to，on等，可以不译。如：
The barometer is a good instrument for measuring air pressure.充气压力计是测量充气压力的好仪器。
The air was removed from between the two pipes.两根管子之间的空气已经抽出。
Answers to questions 2 and 3 may be obtained in the laboratory.问题2和3的答案可以在实验室里得到。
Most substances expand on heating and contract on cooling.大部分物质热胀冷缩。
③表示与主语有关的某一方面、范围或内容的介词有时不译，可把介词的宾语译成汉语主语。如：
Something has gone wrong with the engine.这台发动机出了问题。
Gold is similar in color to brass金子的颜色和黄铜相似。
Its never occurred to me that bats are really guided by their ears.我从未想到蝙蝠居然是靠耳朵引路的。
④不少of介词短语在句中作定语。其中of总是不译。如：
The change of electrical energy into mechanical energy is done in motors.电能变为机械能是通过电动机达成的。
Some of the properties of cathode rays listed below.现将阴极射线的一些特质开列如下。
