职称英语语法辅导：状语从句

　　一、状语从句的概念和类别

　　状语从句指句子用作状语时，起副词作用的句子。它可以修饰谓语、非谓语动词、定语、状语或整个句子。根据其作用可分为时间、地点、原因、条件、目的、结果、让步、方式和比较等从句。状语从句一般由连词引导，也可以由词组引起。从句位于句首或句中时通常用逗号与主句隔开，位于句尾时可以不用逗号隔开。

　　二、考点聚焦

　　1、时间状语从句

　　as、when、while用法

　　as表示当的时候，往往和when/ while通用，但它着重强调主句与从句的动作或事情同时或几乎同时发生。

　　She came up as I was cooking。

　　The runners started as the gun went off。

　　when:既可以表示在某一点的时候，又可表示在某一段时间内，主句与从句的动作或事情可以同时发生也可以先后发生。

　　It was raining when we arrived。

　　When we were at school, we went to the library every day。

　　while意思是当的时候或在某一段时间里。主句中的动作或事情在从句中的动作或事情的进展过程中发生，从句中的动词一般要用延续性动词。在when表示a period of time时，两者可以互换。

　　Please dont talk so loud while others are working。

　　He fell asleep while/when reading. Strike while the iron is hot。

　　引导时间状语从句的连接词除上述外还有：

　　①till, not until , until, before, since

　　Dont get off the bus until it has stopped。

　　He waited for his father untilit was twelve oclock。

　　It will be five years before he returns from England。

　　②hardly / scarcely when, no sooner than, as soon as once

　　表示一就

　　As soon as I have finished it , Ill give yu a call。

　　Once you show any fear, he will attack you。

　　We had hardly got / Hardly had we got into the country when it

　　began to rain。

　　No sooner had he arrived / He had no sooner arrived than she started complaining。

　　③directly, immediately, the moment, the minute that 一就

　　He made for the door directly he heard the knock。

　　④each time, every time, by the time

　　Each time he came to my city, he would call on me。

　　注意：表示未来情况，主句用将来时，从句用现在时。

　　2、让步状语从句

　　although与though可以引导让步状语从句，不能与but连用，但可以与yet连用。

　　Although they are poor,they are warm-hearted。

　　even if或even though引导让步状语从句，表示即使，纵然，用来使人注意下文所强调内容的性质。

　　Ill get there even ifI have to sell my house to get enough money to go by air。

　　no matter后接上who、what、where、how等疑问词，也可以在这类疑问词后面加上ever构成whoever、whatever、wherever、however等。

　　Dont trust him, no matter what / whatever he says。

　　Whoever breaks the law will be published。

　　No matter how hard the work is, youd better try to do it well。

　　as也可以引导让步状语从句。要用倒装。

　　Child ashe is, he knows a lot。

　　Much as I like it, I wont buy。

　　Try as he would, he couldnt lift the heavy box。

　　3、原因状语从句：because, for, as, since, now that

　　表示不知道的原因时用because,即说话人认为听话人不知道，因此because从句是全句最重要的部分，通常它被置于主句之后。

　　You want to know why Im leaving? Im leaving because Im full。

　　for虽然表示不知道的原因，但其语气较because要弱得多，是可说可不说的话，它只能置于主句之后，这时，for是并列连词。如果不是因果关系，而是对前面主句的内容加以解释或推断时，只能用for。如：Its morning now, for the birds are singing。

　　表示已经知道的原因时用as或since,即某种原因在说话人看来已经很明显，或已为听话人所熟悉，因此它是句中不很重要的部分。since要比as正式一些，它们通常被置于语句之前，但有时却相反。

　　Seeing all of the children already seated, he said,Since everyone is here, lets start。

　　下列情况下只能使用because:

　　①在回答why的问句时;

　　②在用于强调句型时;

　　③被not所否定时。

　　4、地点状语从句：where, wherever

　　Make a mark wherever you have any questions。

　　We will go where the Party directs us。

　　5、目的状语从句：that, so that, in order that

　　注意：目的状语从句的谓语动词常与情态动词连用，否则可能是结果状语从句。不可置于句首。

　　6、结果状语从句：that, so that, so that, such that

　　注意：so + 形容词/副词 + that从句;such +　名词 + that从句。

　　7、方式状语从句：as, as if

　　Ill do as I am told to。

　　It looks as if it is going to rain。

　　8、比较状语从句：than, as

　　9、条件状语从句：if, unless, so long as, in case, once, a far as, on condition that。

　　注意if与unless的区别：不能用and连接两个unless从句，即不能有 unless ,and unless 。但if not and if not却不受此限。

　　You wont lose your weight unless you eat less and unless you exercise more。

　　但可以说 unless you eat less and exercise more。

　　10、注意状语从句中从句的省略现象

　　连接词 + 过去分词

　　Dont speak until spoken to。

　　Pressure can be incrased when needed。

　　Unless repaired, the washing machine is no use。

　　连词 +　现在分词

　　Look out while crossing the street。

　　连词 + 形容词/其他

　　常见的有it necessary、if possible、when necessary、if any等。

　　三、经典题目解析

　　选择填空

　　1. I dont think Ill need any money but Ill bring some ____________。

　　A.as last B.in case C.once again D.in time

　　解析：答案为B。句意为带些钱以防万一，只能选择in case。引导的条件状语从句，后面省略了I should need it。

　　2. The WTO cant live up to its name _________ it doesnt include a country that is home to one fifth of man-kind。

　　A.as long as B.while C.if D.even though

　　解析：答案为C。本题考查状语从句的用法。句意为假如世贸组织不包括占世界人口五分之一的中国的话，那它就名不副实。as long as语气过于强烈，while和even though不符合句意。

　　3、Someone called me up in the middle of the night, but they hung up_________I could answer the phone。

　　A.as B.since C.before D.until

　　解析：答案为C。题意为：半夜里有人打来电话，我没来得及就挂了。but暗示在接话前就挂了。