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1、复合句【语法要点】复合句是由一个主句加一个或几个从句所构成的句子。从句只用作句子的一个成分，不能独立。根据从句在句子中的作用，可分为名词性从句、定语从句和状语从句三类。（一）名词性从句名词性从句包括主语从句、表语从句、宾语从句、同位语从句。其关联词有连接词that、if 、whether ；疑问代词 who、what、which 和疑问副词 when、where、how、why 等。1.名词性从句句法结构：主语从句 That he will come is certain.（that 不可省）Whether she is coming or not doesnt matter too much
2、.（不能用 if）宾语从句I think（ that） he will be all right in a few days.I went in and asked if（=whether）they had a cheap suit.I wonder whether（不能用 if）it is true or not.表语从句The fact is（that）I have never been there.The question is whether（不能用 if）it is worth doing.从属连词thatwhether 同位语从句The fact that she had not
3、said anything surprised all of us.They asked me the question whether the work was worth doing.主语从句Who will help him is not known.What he said is very important.Which side will win is not clear.宾语从句（1）作及物动词的宾语。例如：I really dont know what he is doing.Do you know who/whom they are waiting for?He asked w
4、hose dictionary it was.He cant tell which method they will use for the experiment.（2）作介词的宾语。例如：Pay attention to what the teacher said.I wondered to whom he had given the letter.连接代词thatwhowhomwhosewhich 表语从句That is what he is worried about.The question is who will come here.The question is which tea
5、m will win the match.主语从句 Where she has gone is not known yet.When they will start is not known yet.Why he did it wasnt quite clear.How he became a great scientist is known to us all. 宾语从句 I dont know where we are going to have the meeting.Please tell me when we shall discuss our work plan.Do you kn
6、ow why he said that?Will you tell me how I can get to the railway station?表语从句 That is where he was born.This is why he is late.This is how he did it.The question is when he will be back.连接副词wherewhenwhyhow同位语从句I have no idea when he will come back.You have no idea how worried I was.The problem is w
7、here we can get so much money.2.名词性从句的其它用法：1）if 不能引导表语从句。连接代词 who、what、whose 、which 不能引导同位语从句。2）有时 as、as if/though、because 也可以引导表语从句，能跟表语从句的谓语动词一般为系动词 be、seem、look 等。例如：Things are not always as they seem to be. 事情并不总是像表面上看来的那样。It looks as if it were going to rain. It is because you eat too much. 3）介
8、词宾语不可以用 which 来引导，而要用 what 来引导。例如：We can learn what we did not know. He will talk to us about what he saw in the U.S.4）连词 that 引导的名词性从句除能用在 except、but 、in 后之外很少作介词的宾语， 。其它一些介词的宾语从句如果由连词 that 引导，则需用 it 先行一步作形式宾语。例如：He is a good student except that he is careless.You may depend on it that they will su
9、pport you.5）若主句谓语动词是及物动词 make、find、think、see、hear 等，则把宾语从句置于宾语补足语之后，用 it 作形式宾语。例如：We find it necessary that we practise spoken-English every day.6）某些作表语的形容词或过去分词后常接宾语从句，如sure、happy、glad 、certain 、pleased 、afraid、surprised 、satisfied 等，连词 that 可省略，有的语法书称之为状语从句。例如：I am sure that he will succeed.I am a
10、fraid you dont understand what I said.Mother was very pleased her daughter had passed the exams.7）连接代词 whoever、whatever、whichever 也可引导宾语从句。例如：I will show you whatever you want to see.You may choose whoever you like. I will take whichever fits the sockets.（插座）8）同位语从句一般跟在某些表示抽象概念的名词后面，用以说明名词所表示的具体内容。常
11、跟同位语从句的名词主要有：idea、news、fact、promise 、answer 、belief、condition、 doubt、fear 、hope、order 、problem、proof、question 、 reply、report、suggestion、thought、 truth 等。由连词 that 引导同位语从句既无语法功能，也无词汇意义，只是引导词；由连词 whether 引导同位语从句无语法功能，但有词汇意义“是否” ；由连词 when、where、how 引导同位语从句在句中分别作作时间、地点和方式状语。注意关联词只能用 whether 不能用 if 表示“是否”
12、的情况如下：A)在表语从句和同位语从句中。 例如：The question is whether the film is worth seeing.The news whether our team has won the match is unknown.B)在主语从句中，只有 it 作形式主语时 whether 和 if 均可。否则，也只能用 whether。例如：Whether we shall attend the meeting hasnt been decided yet.It hasnt been decided whether/if we shall attend the me
13、eting.C)在介词之后（介词往往可以省略） 。例如：It all depends (on) whether they will support us.D)后面直接跟动词不定式时 。例如：He doesnt know whether to stay or not.E)与 or not 连用时。例如：We didnt know whether or not she was ready. 关联词 if、whether 均可使用的情况如下：A)引导宾语从句，但当宾语从句是否定句时，一般用 if 引导。例如：I wonder if/whether the news is true or not. I
14、 dont care if it doesnt rain.B)在“be+形容词”之后。例如： He was not sure whether/if it is right or wrong.用 if 引导宾语从句如果会引起歧义，应避免使用 if 而用 whether。试比较：Please let me know if you want to go. Please let me know whether you want to go.（if 从句既可理解为宾语从句，也可理解为条件状语从句）doubt 作“怀疑”解接宾语从句时，主句为肯定句用 whether 或 if，主句为否定句或疑问句用tha
15、t。10）it 作形式主语that 所引导的主语从句常由代词 it 作形式主语。且 wh-系列引导词引导的从句均可。例如： It makes everyone happy that the girl is still alive. It doesnt matter too much whether hes coming or not.It is still open to question who is to head the group. 谁领导这个小组还没定下来。 常以 it 作形式主语的句型有：It +be+形容词(obvious、true、natural 、surprising、goo
16、d 、wonderful、funny、possible、likely 、certain、probable)+that 从句It +be+名词词组(no wonder、an honour、a good thing、a pity、no surprise)+that 从句It +be+过去分词(said、reported、thought 、expected、decided、announced、arranged)+that 从句It +seem、happen 等不及物动词及短语+that 从句It +doesnt matter(makes no difference, etc)+连接代词或连接副词引导的主语从句当 that 引导的主语从句出现在疑问句中时，也要以 it 作形式主语，而把主语从句后置。例如：Is it true that the scientist will give us a lecture next week?（二）定语从句在复合句中修饰名词或代词的从句叫定语从句。
