【摘 要】电力科技英语文献中常常含有结构复杂的长句，要理解这些长句的关键往往在于正确地把握句子的主谓结构。从英语名词的数、英语主谓结构基本类型、定语从句主谓结构等方面入手，可以较好地掌握英语主谓结构分析的方法，从而提高电力科技英语阅读理解的能力。
【关键词】电力科技英语；名词的数；主谓结构分析
1．引 言
一般来说，英语的主谓结构与汉语相同：主语在前，谓语在后。但是，由于英语名词有单复数的变化，加上英语中作主语的名词和与作谓语的动词之间常常可以插入定语和状语，有时，这些定语或状语由较长的从句担任；再有英语中还有倒装结构，作主语的名词放到了作谓语的动词之后；这一切都为正确找出主句的主谓结构带来了困难。请看下面3句选自电力科技英语文献的句子：
[1] The 20th century has witnessed a big expansion of electrical power generation and distribution. The general pattern has been toward ever-larger units of production, using steam from coal- or oil-fired boilers. Economies of scale and the greater physical efficiency achieved as higher steam temperatures and pressures were attained both reinforced this tendency.
[2] Among the more common reasons why certain generators are necessary for reliable system operations are the need to maintain adequate voltages, reactive power requirements, reserve requirements, and unit commitment requirements.
[3] In recent years many discoveries have been made in this field which greatly faciliate the study of electricity and gives a new conception of the nature of matter.
在句[1]中，斜体部分句子的主语是Economies of scale and the greater physical efficiency。但谓语何在？句[2]中的两个are，哪一个是谓语动词，主语又在哪里？句[3]中斜体部分的which是定语从句的主语，但它指代什么？这3个实例表明：电力科技英语文献中句子的主谓结构必须认真分析才能真正弄清，从而为正确理解句子奠定基础。
下面从英语名词的数、基本的英语主谓结构类型、定语从句的主谓结构判别等方面讨论英语主谓结构的分析方法。
2．英语名词的数
英语句子的主语主要由名词和代词来担任，代词相对而言较为简单，而英语的名词与汉语不同，在形式上有数的变化，即在词尾加上-s表示复数；同时，谓语动词根据主语的单复数也发生相应的单复数的变化。这一方面使语言变得复杂，但另一方面也为我们正确识别主谓结构提供了依据，例如：
[4] The expanding gas coming from the turbine and movng along the jet nozzles continues to expand and accelerate to form a high velocity.
句中谓语动词continues加上了-s，提示主语一定是单数，所以它的主语不可能是前面的the jet nozzles，而是the expanding gas。
在英语语法中，有关名词的数的内容很多，但从帮助分析英语主谓结构的目的出发，主要应该掌握下列要点。
2．1．-s结尾的名词不一定是复数
在英语中，部分以-s结尾的名词需要动词以单数形式与其保持一致，主要有：
（1）表示学科含义的词，例如：
[5] Electronics（电子学）is the basis of all communications system.
[6] Thermodynamics（热力学）deals with the relationship between heat and other forms of energy.
又如：mechanics（力学）acoustics（声学），informatics（情报学，信息学），mathematics（数学），optics（光学），physics（物理学），plastics（塑料学）等等。
（2）表示疾病名词的词，例如：
[7] Diabetes（糖尿病）is a common disease.
[8] Generally measles（麻疹）occurs in children.
又如：arthritis（关节炎），shingles（带状疱疹）等等。
（3）某些专有名词，例如：
[9] General Motors （通用汽车公司）produces many different types of cars.
[10] The United States（美国）exports a lot each year.
又如：the United Nations（联合国），the New York Times（纽约时报）等等。
2．2．-s结尾的单词可以是单数，也可以是复数
在英语中也有相当一部分以-s结尾的名词，在一定的上下文中，既可以是单数，也可以是复数，例如：
[11] A series of accidents（一系列事故—）has been reported in that power plant.
[12] There are two series of transformers（两种系列的变压器）used in this project。
[13] Is this the only means （唯一的方法）to produce electricity in this area?
[14] There are various means（各种方法）of increasing our power production.
又如：steel-works（钢铁基地），species（物种），headquarters（指挥部）等等。
一般来说，确定这种名词的单复数，主要看它们前面有关数量的修饰词，a，the only等提示作单数用，two，various提示作复数用。
2．3．不是以-s结尾的名词也可以是复数
如前所述，-s结尾的名词不一定是复数；同样道理，不是以-s结尾的名词也不一定全是单数。英语中部分非-s结尾的名词要作为复数使用，例如：
[15] The committee（委员会）are divided in their opinion about the construction of a nuclear power station in that densely-populated area.
[16] Do vermin（害虫）do harm to electrical installations?
又如：police（警察），cattle（牲口），staff（员工）等等。
2．4．单位词、百分数、分数等的使用
有时，名词需要与单位词、百分数或者分数一起使用，这时谓语动词的单复数就需要发生相应的变化。一般来说，可以遵循下列句型：
单数单位词 + of + 名词：单数谓语动词
复数单位词 + of + 名词：复数谓语动词
百分数/分数 + of + 可数名词复数：复数谓语动词
百分数/分数 + of + 不可数名词：单数谓语动词
例如：
[17] A large piece of land is marked out for the construction of a coal field.
[18] Three boats of coal are needed.
[19] Only 25 % of the capital is American-owned
[20] One-fifth of the generators are being repaired.
3．基本的英语主谓结构类型
从便于识别与阅读的角度看，可以将英语中由名词充当主语的主谓结构分为下面几种类型：
单个名词 + 谓语动词
单个名词 + 后置定语/状语 + 谓语动词
（3） 并列名词 + 谓语动词
（4） 并列名词 + 后置定语/状语 + 谓语动词
（5）谓语动词 + 名词
另外，还有下列由非谓语动词或从句充当主语的类型：
（6）不定式（短语）+ 谓语动词
（7）动名词（短语）+ 谓语动词
（8）主语从句 + 谓语动词
单个名词 + 谓语动词
单个名词作主语是最简单的主谓结构，只要注意做主语的名词本身的单复数就可以了，例如：
[21] The 20th century has witnessed a big expansion of electrical power generation and distribution.
[22] The small direct-current generators were abandoned in favour of alternating-current systems.
并列名词 + 谓语动词
从句子含义的角度出发，这里所指的并列名词有三类：一是指由and、or等单个并列连接词连接起来作主语的名词，第二类指由not only… but also，neither… nor，either… or等组合并列连接词连接起来作主语的名词，第三类是指由as well as，along with，together with，in addition to，instead of等短语介词连接起来的名词，确切地说，第三类在结构上并不是并列关系，但由于在含义上有并列的意思，在结构上与并列结构也极为相似，所以归在这里一起讨论。
对于第一类并列主语，用and连接起来的主语，谓语动词一般用复数。
[23] The rotor shaft and the field structure are made of a solid alloy steel forging in which slots are machined to accept the field coils, as shown in Figure 2.
用or连接起来的主语，谓语动词的单复数由or后的名词单复数决定。
[24] A large unit or several small units are needed.
[25] Several small units or a large unit is needed.
对于第二类并列主语，谓语动词均与组合并列连接词后面的一个主语在数上保持一致。
[26] Not only coal and oil but also falling water is being used to produce electricity.
[27] Either falling water or coal and oil are being used to produce electricity.
[28] Neither I nor he likes to work there.
对于第三类并列主语，谓语动词的单复数根据as well as等短语介词前的名词的单复数而定。
[29] The machine as well as its auxiliary devices is imported.
[30] All the pipes along with the boiler need to be checked.
3.3 名词 + 后置定语/状语 + 谓语动词
名词加上后置定语，或者在主语与谓语之间插入状语，句子会变得复杂一些。一般来说：主语的后置定语常由介词短语、不定式短语、分词短语、定语从句来充当；状语则往往需要用逗号撇开。例如：
[31] The various manifestations of electricity are the result of the accumulation or motion of numbers of electrons.
介词短语of electricity作主语manifestations的后置定语。一方面，manifestations与are在数上保持一致，另一方面，也提示它们之间存在主谓关系。
[32] The hydroelectric power using a fall of water to drive water turbines has been developed to generate electricity where the climate and topography make it possible to combine production with convenient transmission to a market.
分词短语using a fall of water to drive water turbines放在主语the hydroelectric power与谓语动词has been developed之间作后置定语。
[33] Another important factor to be taken into consideration is that current strength is equal at certain points in a series circuit.
不定式短语to be taken into consideration插在主语another important factor与谓语动词is之间作后置定语。
[34] The electric current which we are talking about is simply a flow of electrons.
which we are talking about是句子主语the electric current的后置定语。
[55] Such magnetism, because it is electrically produced, is called electromagnetism.
原因状语从句because it is electrically produced插在主语与谓语动词之间。
[36] Atoms, small as they are, are made up of still smaller units known as “subatomic participles”.
主语atoms与谓语动词are made up of之间的small as they are是一个让步状语从句。
一般来说，由于定语从句和状语从句有连接词在句首，比较容易识别，因此被它们分隔开的主语与谓语动词也比较好找，如[34]，[35]和[36]。而插在主语与谓语动词之间的介词短语、分词短语和不定式短语，则需要认真分析句子成分才能加以识别，如[31]，[32]和[33]。有时，主语与谓语动词之间的后置定语不止一个，这就使句子变得更为复杂，主谓之间关系的分析需要更加仔细，例如：
[37] The communication of digital data among computers connected by wire, microwave, and satellite circuits is now a major enterprise that has built a strong bond between computer and communications specialists.
句子主语the communication与谓语动词is之间插进了带有过去分词短语connected by wire, microwave, and satellite circuits的介词短语of digital data among computers。
3．4．谓语动词 + 名词
这一类型是倒装句，there be句型也在此列。例如：
[38] From these simple concepts has developed a sophisticated technique that many of the electrical companies have now adopted to make the power industry less vulnerable to the limited sources of energy.
介词短语from these simple concepts为首，是倒装句，谓语动词是has developed，提示句子主语是单数，即后面的a sophisticated technique。
[39] There are four ways for transmitting power from the electric motor to the spindle.
There are是谓语动词，are提示主语是后面的复数名词ways。
3. 5． 不定式（短语）+ 谓语动词
不定式短语作主语看作单数，在分析谓语动词的单复数时，注意不要受不定式自己宾语的干扰，例如：
[40] To use any of these fuels needs our serious consideration.
主语是不定式短语，而不是fuels。
[41] To transmit electromagnetic waves takes energy.
当然，两个或两个以上不定式短语并列作主语，谓语动词用复数形式：
[42] To use any of these fuels and to reuse this boiler both need our serious consideration.
3. 6． 动名词（短语）+ 谓语动词
与不定式短语作主语一样，动名词短语作主语也看作单数，在分析谓语动词时，也要注意不要受动名词自己的宾语的干扰；并列的动名词短语作主语，谓语动词也要用复数形式，例如：
[43] Using any of these fuels has an effect on the environment, as these videos show, but all of these effects can be minimized so that these fuels can continue to be used.
句子主语是using any of these fuels，谓语动词是has。
[44] Generating current at a lower frequency and then boosting it to a higher frequency are more efficient.
句子主语是两个并列的动名词短语：generating current at a lower frequency和then boosting it to a higher frequency。
3．7．主语从句+谓语动词
主语从句作主语一般看作单数，并列的主语从句一般应该用复数谓语。例如：
[45] Whether this unit will operate efficiently remains to be seen.
[46] What potential energy and kinetic energy means and how we explain these two terms have been mentioned in this article.
主语为两个分别由what和how引导的主语从句，所以谓语动词用复数形式have；反过来也可以这样认为：正因为谓语动词是复数，所以一定有两个或两个以上的主语。
4．定语从句的主谓结构的判别
由于定语从句的主语可能是由that或which等连接词来充当，that或which到底指代什么，有时需要通过主谓结构的分析才能搞清，例如：
[47] This process enhances the overall thermal efficiency of energy conversion to about 50 percent--as opposed to conventional processes, which have an efficiency of about 36 to 38 percent.
定语从句的谓语动词是have，提示连接词which指代复数名词，即processes。
[48] The lines of high-voltage transmission systems are usually composed of wires of copper, aluminum, or copper-clad or aluminum-clad steel, which are suspended from tall latticework towers of steel by strings of porcelain insulators.
定语从句的谓语动词是are，提示连接词which指代的也是复数名词，而不是前面的steel，仔细分析可以发现：which指代复数名词wires。
5. 结束语
现在回过头来让我们用上述方法分析一下“引言”部分的三个例句。在句[1]中，主语比较容易确定，是Economies of scale and the greater physical efficiency。但识别主谓结构的关键是找谓语动词。从例句中可以找到achieved，were attained和reinforced三个动词。由于achieve是及物动词，后接as …，没有宾语，显然不是谓语，只是过去分词做 efficiency的后置定语；as是连接词，后接从句，因此，were attained是as从句的谓语；由此可见：主句的谓语应该是reinforced，both提示主语有两个，即：Economies of scale and the greater physical efficiency。这是基本主谓结构类型3。在句[2]中，介词短语开头，是一个倒装句。由于谓语是are，提示主语是复数，即后面的the need和unit commitment requirements。这是基本主谓结构类型4。句[3]是个牵涉到定语从句主谓结构判断的句子。Which引导的定语从句中，which作主语，这是很清楚的，但which指什么？通过定语从句主谓结构的分析，可以帮助我们理解which所指。由于which引导的定语从句的谓语动词是ficiliate，没有加-s，指示which代表复数名词，朝句子前面部分看，可以确定which指代复数名词discoveries，而不是紧靠在它前面的field。
综上所述，从英语名词的数、基本的英语主谓结构类型、定语从句的主谓结构判别等方面入手，可以较好地把握英语句子主谓结构的分析，从而提高电力科技英语文献的阅读能力。
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