英语定语从句与状语从句的辨析
英语定语从句与状语从句的辨析
英语定语从句与状语从句的辨析
键词：As引出的从句 主语 谓语动词 宾语 表语
摘要:As用作关系代词,可以代替整个主句,在从句中作主语、宾语和表语。As还可引出限定性定语从句和非限定性定语从句。As用作关系副词,可以引出时间状语从句、原因状语从句、比较状语从句、让步从句、方式状语从句和插入句。
As是英语里一个比较常见的用法繁多的词,它和其它词的搭配关系也很广泛。现有的语法书中对as引导出的从句规律阐述不多,笔者经过多年的教学实践和研究对as此种用法和功能有了新的认识。由于as用作关系代词又用作关系副词的这种双重职能确定着从句和主句在意义上的关系。例如:①I decided to go with as he was notwell.②John is very healthy as are his sisters.以上两句究竟是哪一类从句?是时间从句、原因从句、比较状语从句还是表语从句……?我们一时难以确认。为了正确理解和准确翻译文章和句意,我们有必要对as从句予以辨别,确定其性质。as引导的从句有:定语从句、原因状语从句、让步状语从句、方式状语从句、时间状语从句、比较状语从句、表语从句和插入句。
一、定语从句与状语从句的辨析A.as从句前有the same或such的,属定语从句,为限制性定语从句。例如:①He works in the same shop as I do.②She eats only such food as the doctor allows himto eat.(两句中的as在从句中分别作do和eat的宾语)③Such passengers as survived the explosion weredrouned.(as在从句中作主语)as从属连词引导的定语从句与状语从句的根本区别在于:它在定语从句中担任主语、宾语或表语等句法成分。在状语从句中却不担任这类成分。因此,我们暂时把as拿掉从句语法结构完整的,为状语从句,否则为定语从句。例如:①As the glass cools,it becomes thick like syrup.(as在从句中不担任主语、宾语、表语,是时间从句)②Infrared and light waves are transverse waves,asalso are radio waves.(从句缺少表语,as担任了表语,是定语从句)B.as在引导的非限制性定语从句中,所指的是它前面的整个主句,也可能指先行词。它在从句中作主语和宾语。例如:①John was admitted into the university,as we hadhoped.(as指的是它前面的整个句子,在从句中作hoped的宾语)②Water,as is known to all,is a liquid.(as指先行词water,在从句中作主语)as引导的非限制性定语从句,可以位于主句的主语和谓语之间,而它引导的状语从句不能位于其间。所以位于主句的主语和谓语之间的、前后都有逗号的as从句,as又在从句中充当句法成分的为定语从句。(上述例句②)
二、原因状语从句和时间状语从句的辨析位于句首的由单个as引导的状语从句只能是时间和原因状语从句。位于句末的在排除了方式状语从句的可能性之后,也只能是时间和原因状语从句。例如:①As heat energy makes things move,it is a form ofenergy.(原因从句)②The volume varies as the temperature increases.(时间状语从句)A:凡是as引导的状语从句的时态与主句不一致的,一般为原因状语从句。例如:①As this question is of great interest,we will dis-cuss it once again.(从句是一般现在时,主句是一般将来时,是原因状语从句)②In such regions it is particularly important to ob-tain an accurate indication of the duration of intense rain-falls,as the resulting stream flow will usually determineinsulator the spillway capacity required for safety of thestructure.(从句是一般将来时,主句一般现在时,是原因从句)B:主句或as从句的谓语含有情态动词的,as从句一般为原因状语从句。例如:①As all substances conduct electricity to some ex-tent,an ideal insulator can not be completely realized inpractice.(主句的谓语有情态动词为原因从句)②These reports should be utilized when studying aproject as they are the most authoritative records avail-able.(主句谓语含有情态动词,原因状语从句)C.as可引导时间从句。凡是谓语表示一种连续性动作的as从句,一般都是时间状语从句;表示主语特征、状态或表示不连续动作的as从句,一般为原因从句。另外,用as引导的原因从句与主句一般具有明显的因果关系。例如:①As they are neutral electrically,they are calledneutrons.(表示特征,原因从句)②As the two bodies are in close contact,heat istransferred by conduction.(表示状态,原因从句)③As the earth spins on its axis and revolves aroundthe sun,it attracts the air around it.(从句谓语动词表示连续动作,是时间状语从句)
三、as引导让步从句谓语一部分置于句首的as从句,一般都是让步状语从句。例如:①Young as●he is,he knows a lot.②Search as●theywould,theywould find.③Child as●he was,he knows something of electrici-ty.
四、as引导方式状语从句just as引导的从句只能是方式状语从句,单个as引导的方式状语从句,其位置只能在主句之后,因为方式状语从句谓语动词表示的概念与主句谓语所表示的概念相同,所以其谓语常采取省略形式,或者只有一个助动词、情态动词或者只有一个be,在与主句谓语动词相同的情况下,它的谓语往往用do代替。这些是as引导原因从句或时间状语从句所不可能有的。因此,当位于主句之后的as状语从句的谓语仅有一个助动词或者be,或者为do时,一般都是方式状语从句。例如:①Just as electrans and nucleus together build atom-s,groups of atoms build molecules.②A steamengine runs in one direction only and cannot be reversed as a reciprocating engine can.③Airwww.51lunwen.com occupies space as any other gases do.④Light waves are different in frequency as soundwaves are.
五、由as…as;not so…as或not as…as引导的从句是比较状语从句例如:①He works as hard as we.②Line AB is not so long as line CD.在as…as;not so…as;not as…as的结构中必需用形容词和副词原级才是比较状语从句。下面这句中as…as之间是名词为定语从句。例如:As manypeople as we found were taken to the hospital.(as在从句中作宾语)
六、用as引出表语从句(…的那样;象…那样)例如:①It may be as you say.②Things are not always as they seem to be.上述两例①②中as you say和as they seem to be非作表语从句分析不可,否则该句子就没有表语了。
七、用as引出插入句as:“如同…那样;正如…那样”。as可以引出一个附带说明的句子,表说话人说出这句话的根据,或对这句话的态度作出某种解释和评论,这种成分叫插入句,它一般必须前、后用逗号隔开。as在从句中不担任成分。例如:①The difference,as I see it,is one of method andnot of principle.②This old machine must be,as it appears tome,re-placed by a newone.③David,as we know,writes short stories.就例③来看,as引出的从句前后有逗号隔开,作插入句的可能性就比较大了,但是,作插入句还缺少一个宾语(作know的宾语),可是就其从句意思来看,倒可译为“据我们所知”。如果把该从句分析为as代替整个主句意义的定语从句,也未尝不可。因此,希望不必过多地抠语法分析,能领会其意就可以了。总而言之,as用作关系代词,可以代替整个主句,并且在从句中作主语、宾语和表语。引出的限定性定语从句多在the same as和such…as的句子后面;引出的从句前后有逗号分开的为非限制性定语从句。as用作关系副词,可以引导时间状语从句、原因状语从句、比较状语从句、让步状语从句、方式状语从句和插入句。
如果只有单个as引出的各种从句前后没有象such,so,same,as,that,many和much之类的有关词的搭配和衬托,判别从句的语法意义就要靠上下文和逻辑性来进行。另外各种从句都有各自的语法结构特点和比较稳定的语法位置。只要我们用心观察分析就能够辨别出该从句的性质,使我们能够较快地予以正确理解文意,准确翻译了。
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