广泛使用被动语句
根据英国利兹大学John Swales 的统计,科技英语中的谓语至少三分之一是被动态。这是因为科技文章侧重叙事推理,强调客观准确。第一、二人称使用过多,会造成主观臆断的印象。因此尽量使用第三人称叙述,采用被动语态,例如:Attention must be paid to the working temperature of the machine.应当注意机器的工作温度。而很少说:You must pay attention to the working temperature of the machine .你们必须注意机器的工作温度。此外,如前所述,科技文章将主要信息前置,放在主语部份。这也是广泛使用被动态的主要原因。试观察并比较下列两段短文的主语。
We can store electrical energy in two metal plates separated by an insulating medium. We call such a device a capacitor, or a condenser, and its ability to store electrical energy capacitance .It is measured in farads.
电能可储存在由一绝缘介质隔开的两块金属极板内。这样的装置称之为电容器,其储存电能的能力称为电容。电容的测量单位是法拉。
这一段短文中各句的主语分别为:
Electrical energy
Such a device
Its ability to store electrical energy
It (Capacitance )
它们都包含了较多的信息,并且处于句首的位置,非常醒目。四个主语完全不同,避免了单调重复,前后连贯,自然流畅。足见被动结构可收简洁客观之效。
非限定动词
如前所述,科技文章要求行文简练,结构紧凑,为此,往往使用分词短语代替定语从句或状语从句;使用分词独立结构代替状语从句或并列分句;使用不定式短语代替各种从句;介词十动名词短语代替定语从句或状语从句。这样可缩短句子,又比较醒目。试比较下列各组句子。
A direct current is a current flowing always in the same direction.
直流电是一种总是沿同一方向流动的电流。
Radiating from the earth, heat causes air currents to rise.
热量由地球辐射出来时,使得气流上升。
A body can more uniformly and in a straight line,there being no cause to change that motion.
如果没有改变物体运动的原因,那么物体将作匀速直线运动。
Vibrating objects produce sound waves ,each vibration producing one sound wave.
振动着的物体产生声波,每一次振动产生一个声波。
In communications, the problem of electronics is how to convey information from one place to another.
在通讯系统中,电子学要解决的问题是如何把信息从一个地方传递到另一个地方。
Materials to be used for structural purposes are chosen so as to behave elastically in the environmental conditions.
结构材料的选择应使其在外界条件中保持其弹性。
There are different ways of changing energy from one form into another.
将能量从一种形式转变成另一种形式有各种不同的方法。
In making the radio waves correspond to each sound in turn, messages are carried from a broadcasting station to a receiving set.
使无线电波依次对每一个声音作出相应变化时,信息就由广播电台传递到接收机。
大量使用名词化结构
《当代英语语法》(A Grammar of Contemporary)在论述科技英语时提出,大量使用名词化结构(Nominalization)是科技英语的特点之一。因为科技文体要求行文简洁、表达客观、内容确切、信息量大、强调存在的事实。而非某一行为。
Archimedes first discovered the principle of displacement of water by solid bodies.
阿基米德最先发展固体排水的原理。
句中of displacement of water by solid bodies 系名词化结构,一方面简化了同位语从句,另一方强调displacement 这一事实。
The rotation of the earth on its own axis causes the change from day to night.
地球绕轴自转,引起昼夜的变化。
名词化结构the rotation of the earth on its own axis 使复合句简化成简单句,而且使表达的概念更加确切严密。
If you use firebricks round the walls of the boiler, the heat loss, can be considerably reduced.
炉壁采用耐火砖可大大降低热耗。
科技英语所表述的是客观规律,因之要尽量避免使用第一、二人称;此外,要使主要的信息置于句首。
Television is the transmission and reception of images of moving objects by radio waves.
电视通过无线电波发射和接受活动物体的图象。
名词化结构the transmission and reception of images of moving objects by radio waves 强调客观事实,而"谓语动词则着重其发射和接受的能力。
后置定语
大量使用后置定语也是科技文章的特点之一。常见的结构不以下五种:
1、介词短语
The forces due to friction are called frictional forces.
由于摩擦而产生的力称之为摩擦力。
A call for paper is now being issued .
征集论文的通知现正陆续发出。
2、形容词及形容词短语。
In this factory the only fuel available is coal.
该厂唯一可用的燃料是煤。
In radiation, thermal energy is transformed into radiant energy ,similar in nature to light.
热能在辐射时,转换成性质与光相似的辐射能。
3、副词
The air outside pressed the side in .
外面的空气将桶壁压得凹进去了。
The force upward equals the force downward so that the balloon stays at the level.
向上的力与向下的力相等,所以气球就保持在这一高度。
4、单个分词,但仍保持校强的动词意义。
The results obtained must be cheeked .
获得的结果必须加以校核
The heat produced is equal to the electrical energy wasted.
产生的热量等于浪费了的电能。
5、定语从句
During construction, problems often arise which require design changes.
在施工过程中,常会出现需要改变设计的问题。
The molecules exert forces upon each other, which depend upon the distance between them.
分子相互间都存在着力的作用,该力的大小取决于它们之间的距离。
Very wonderful changes in matter take place before our eyes every day to which we pay little attention.
(定语从句to which we pay little attention 修饰的是changes,这是一种分隔定语从句。)
我们几乎没有注意的很奇异的物质变化每天都在眼前发生。
To make an atomic bomb we have to use uranium 235, in which all the atoms are available for fission.
制造原子弹,我们必须用铀235,因为轴的所有原子都会裂变。