在英文中,句子中动词的数必须和主词的数互相配合。 如果主词是单数,动词也必须是单数。 复数主词以及由两个以上名词以and 连接而成的复合主词,必须用复数动词,即使主词倒装也是如此。 例如:
The R&D director and sales manager are both at the meeting．
On the agenda were incoming orders, production planning, and delivery schedule．
(1)动词的数必须配合主词的数,而不应配合句子中述词名词或其他名词的数。 例如:
His field of research is molecular biology and neurology．
Computer-aided design systems are an important type of tool used in the product development process．
当句子中出现虚主词结构there is 或there are 时,动词应该和紧跟其后的主词一致。例如:
There is a unique solution to this equation．(主词是solution)
There are several ways to approach this problem．(主词是ways)
(2)两个单数主词之间出现or 或nor 时,必须用单数动词,复数主词之间出现or 或nor时,必须用复数动词。 如果动词中出现由单数主词和复数主词以or 或nor 连接而成的复合主词,则动词的数应该配合最靠近动词的主词的数。 例如:
Raising the temperature or increasing the flow of hydrogen causes the reaction rate to increase．
Neither the experimental results nor the theoretical results are valid．
Either the experimental results or the theoretical analysis is invalid．
(3)冠以every, each 或no 的单数主词必须用单数动词,即使单数动词之间出现and,也是如此。 例如;
No student graduates without having submitted an acceptable thesis．
Every paper, thesis, and letter is stored in this computer．
以-one,-body 以及-thing 结尾的不定代名词(如everyone 及something 等)必须用单数动词。 此外,another, each, either, neither 及one 这些不定代名词也必须用单数动词。 例如:
Another simplified design is that proposed by Thomson (1987)．
(4)代名词all, any, most, more 及some,既可以接单数动词,也可以接复数动词。 这完全取决于这些代名词所指称的是单数名词(通常是不可数的名词),还是复数名词。 例如:
Most of the salt dissolved when the solution was stirred． (most 指salt 这个单数名词)
Most of the trials were successful． (most 指称trials 这个复数名词)
不定代名词none 如同all, most 及some 一样,通常也可以用单数或复数动词,这完全看它所指称的名词而定。 不过,当none 表示“not one”的意思时,即使它表面上好像是指称复数的前述词,我们仍然必须用单数动词。 例如:
None of the students have arrived． (none 指称students)
None of the methods is efficient enough to be used for real-time processing． (none 表示not one 方法,因此用单数动词。 这个句子表示Not one of the methods is efficient enough)．
(5)当关系代名词who,which 以及that 当作关系子句的主词时,子句的动词的数必须和关系代词的前述词的数互相一致。 例如:
The project that has drawn the most funding has yet to produce any concrete results．
Those of you who study diligently are likely to do well on the test．
以one of 开头的片语之后的关系子句,其动词的数必须和关系代名词的前述词的数互相一致。 例如:
Joanie is the only one of the students who has not turned in her paper． (who 指称one,而不是students,注意:of the students 这个片语可以省略,不影响)
She is one of these people who never finish their work on time． (who 指称people,注意:这里的of these people 这个片语不能忽略)
(6)单数主词即使其后紧跟着以as well as, together with, along with, in addition to 以及类似字词开头的片语,仍然是单数。 例如:
The computer hardware as well as the software programs is outdated． (主词computer hardware 是单数名词)
在单数主词和其动词之间出现的字词及片语,并不会影响动词的数。 例如:
One of the advantages of the new computers is that they are easy to use．(www.xing528.com)
(7)在集合名词中,如果集合中的成员行动一致,则用单数动词;如果成员行动不一致,则用复数动词。 所谓集合名词,是单数形的名词,不过却代表一群人或事物,如band, class,committee, crowd, family, faculty, majority, team 以及variety 等。 例如:
The team is playing well today．(球队成员行动一致)
The team are already on their way home．(球队成员各自回家,行动不一致)
A total of 25 samples were collected．(分别收集每件样本)
但是英国和美国习惯不同,为避免混淆,建议最好不把集合名词当成主词。 例如:
原句:A variety of factors have contributed to this growing problem．
修正句:Many factors have contributed to this growing problem．
原句:A series of six experiments were conducted．
修正句:Six experiments were conducted．
(8)有些指称学科或知识的名词(如physics, economics 以及mathematics 等),表面上是复数形,不过却必须用单数动词。 此外,如politics, statistics 以及athletics 这些名词,则可以用单数或复数,完全取决于它们主要是指单数或复数的概念而定。 要注意的是,在正式写作中,data 这个词应该当成复数名词。 例如:
Statistics is taught in the Sociology Department at our university． (Statistics 是单数名词,因为它指称的是一门学科)
Statistics show that special educational programs and psychological therapy are more effective than incarceration in preventing recidivism among juveniles． (Statistics 是复数名词,因为它指的是不同研究中的统计数据)
The experimental data agree with the predictions derived from the theoretical model．
(9)表示固定的量(如金钱,时间,数量等)的名词片语,可以是单数名词,也可以是复数名词,这完全取决于它们指的究竟是一个整体(单数名词),还是整体的个别部分(复数名词)。 例如:
Thirty thousand dollars is a good price for that car．(一个整体)
Forty percent of the budget has been spent already．(一个整体)
The majority in the parliament is liberal．(一个整体)
另外,有少数特殊的复合主词或复数主词,却是指单一的整体,因此必须用单数动词。例如:
R&D is an important aspect of the company’s operations．
Research and development has always been one of Chintech’s strong points．
表示数学关系的复合主词,既可以是单数名词,也可以是复数名词,不过一般作者还是常把它看成单数名词。 例如:
Two plus two equals four．(单数,较常用)
Two plus two equal four．
The number of 用单数动词,不过a number of 却必须用复数动词。 例如:
The number of new accounts opened has increased each year since 1987．
A number of researchers have investigated this problem．
(10)练习
1．Physics________(is/are) a subject that has fascinated him since high school．
2．Each of the samples________(was/were) annealed for 20 minutes．
3．The number of passengers using the airport________(has/have) increased each year since 1984．
4．An attribute name or a class name________(is/are) entered in this dialog box．
5．A number of samples________(was/were) collected from a different geographical region to see whether the phenomenon occurred there as well．
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