主语从句

主语从句可直接位于主语的位置，如果从句较长，谓语又较短，可用it作形式主语，而将从句放在句末。常见的句型有：

1. It is a fact\a pity\a question\good news that…
2. It seems\appears\happened\has turned out that…
3. It is clear\important\likely\possible that…
4. It is said\reported\estimated\has been proved that…

• It is said that comic books create a connection between people of the same generation.
• It seems that the performance is very useful.

what引导的主语从句表示“…的东西时”，一般不用it作形式主语。

1. What we lack is experience.

what,who,when,why,whether等词含有各自的疑问意义，但它们引导的主语从句，都用陈述语序。

• How the plan is to be carried out should be discussed again.
• I did know why I felt like crying.

宾语从句

宾语从句可位于及物动词、介词和某些形容词后。连词that常可省略。介词后一般接疑问词引导的宾语从句。in that(因为),except that(除了),but that(只是）已构成固定搭配，其他介词后一般不接that引导的宾语从句。

• I promised that I would change the situation.
• All this is different from what American young people would say about friendship.
• He is certain that watching so much television is not good for children.
• This article is well-written except that it is a bit too long.

宾语从句后如有宾补，要用形式宾语it来代替，而把宾语从句移至宾补之后。

• He has made it clear that he would not change his mind.

在think,believe,suppose,expect等动词后的宾语从句中，如果谓语是否定的，一般将否定词移至主句谓语上，宾语从句则变成肯定形式。

• He didn’t think that the money was well spent.

表语从句

表语从句出现在结构为“主语+系动词+表语从句”的句子中。表语从句除可用that,what,when,why,whether,how等引导外，还可由because,as if(though)等引导。that常可省略。如主句主语为reason,只能用that引导表语从句，不可用because.

• Perhaps the most important thing to remember is that there is no one common type of life in America.
• The reason why so many people died there is that there were not enough food supplies.
• It looks as if successful international cultural communication will make the world smaller.

同位语从句

同位语从句用于对前面出现的名词作进一步说明，一般用连词that引导，由于先行名词的意义不同，也可用whether,who,when,where,what,why,how等引导。常见的先行名词有fact,idea,belief,news,hope,conclusion,evidence,suggestion,order,problem,report,decision.有时由于谓语较短，将同位语从句位于谓语之后。

• She finally made the decision that she would join the fashion show.
• I had no idea how many books I could borrow at a time.
• The news came that their team had won the championship.

定语从句

定语从句所修饰的先行词可以是名词或代词，也可以是一个句子。定语从句通常位于先行词之后，由关系代词或关系副词引导。

限制性定语从句

限制性定语从句修饰先行词，对先行词起修饰作用，紧接先行词之后，无逗号，若省去，原句意思不完整。引导定语从句的关系代词有who,whom,whose,which,that等。who,whom,whose用于指人，whose有时也可指物，相当于of which；which用于指物；that既可指人也可指物，但只用于限制性定语从句中。关系代词除了引导定语从句，替代先行词外，还在从句中担任主语、宾语、定语等。

• The computers and cables which make up the Internet are owned by people and organizations.
• Those who live alone or who are sick may have trouble in getting close to other people.
• The girl whose parents died in an accident is living with her grandmother.

当先行词是all,anything,everything,something,nothing等不定代词或先行词前有first,last,any,few,much,some,no,only以及形容词最高级修饰时，只能用关系代词that引导从句。

• That is all that I’ve heard from him.
• He’s the first person that I’m going to interview this afternoon.

在从句中作宾语的关系代词常可省略。关系代词紧跟介词，作介词宾语时不可用that，只可用which或whom引导从句，并且不可省略，但当介词位于宾语从句句末时，作为介词宾语的关系代词仍可用that，也可省略。

• This is one of those things with which we have to put up.
• This is one of those things (which\that) we have to put up with.

引导定语从句的关系副词有when,where,why等。关系副词在从句中作状语，意义上相当于一个“介词+which”的结构。

• Even in comic books where(=in which) there are no words,the stories are fully expressed through the drawings.
• No one knows the reason why(=for which) he was so angry that day.

非限制性定语从句

非限制性定语从句既可修饰先行词，也可修饰整个主句，起补充说明作用，与主句之间有逗号隔开，若省去，原句意思不受影响。不可用that引导非限制性定语从句。关系词不可省略。

• Every object has a gravitational pull,which is rather like magnetism.

“介词+which\whom\whose”可引导限制性定语从句，也可引导非限制性定语从句，该结构中介词的选择取决于从句谓语动词的固定搭配，或先行词的习惯搭配。

• This is the computer on which he spent all his savings
• It is written by a person with whom we are all familiar.

as引导的定语从句主要用于“such…as”及“the same…as”的结构中，代替先行词是人或物的名词。as引导非限制性定语从句时，代替整个主句，从句可位于主句之前、之后或中间。

• These are not such problems as can be easily solved.(as代替先行词problems)
• As is mentioned above,no single company or group can control what happens on the Internet.(as代替主语)

状语从句

时间状语从句

引导时间状语从句的从属连词和词组有：

• when,whenever,while,as,after,before,since,till,until,once等。
  • We have learnt quite a lot about it since we came here.
• as soon as,hardly(scarcely)…when,no sooner…than,each(every) time,the moment,immediately(that)等。
  • As soon as I sent an e-mail message,I received positive responses.
  • The moment he heard the good news,he jumped with joy.

地点状语从句

引导地点状语从句的连词是where,wherever.

• Wherever she went,she took her little daughter with her.

原因、结果和目的状语从句

• 引导原因状语从句的从属连词有：because,as,since,now(that),seeing that,considering that,in that等。
  • Considering that he is a freshman,we must say he is doing well.
• 引导结果状语从句的连词有：so…that,such…that,so that,that,so等。
  • Mickey Mouse is so attractive that the children are reluctant to leave.
• 引导目的状语从句的连词有：so that,in order that,for fear that,lest等，从句常使用may,might,can,could,would等情态动词。
  • We got up early this morning so that we could catch the first bus to the railway station.

条件和让步状语从句

• 引导条件状语从句的连词和词组有if,unless,as(so) long as,on condition that,in case,provided(providing) that,supposing等。
  • As long as you have the right equipment,you can use a telephone line to transmit computer data.
• 引导让步状语从句的连词和词组有though,although,whether,even though,even if,no matter what(when,how…),whatever(whenever,wherever,however….)等。though,even if等引导状语从句可转换成含有as的部分倒装结构，具有强调意义。其结构为“形容词（副词、动词、名词）+as+主语+谓语”。
  • No matter what you may say,I would not change my mind.
  • Young as he is,he is quite experienced in this work.(=though he is young)
  • Child as he is,he can speak English fluently.(=though he is a child)

方式状语从句

引导方式状语从句的连词有as,just as,as if,as though等。as if,as though引导的状语从句中，谓语动词常用虚拟语气，表示与事实相反。

• The young man made the experiment just as the teacher had taught him.
• Everything went on as usual as if nothing had happened.