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英语三大从句

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: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 .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 support 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 afraid you don’t 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→①关联词只能用whether不能用if表示“是否”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 hasn’t been decided yet.It hasn’t been decided whether/if we shall attend the meeting.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 doesn’t know whether to stay or not.E)与or not连用时。

例如:We didn’t know whether or not she was ready.②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 don’t care if it doesn’t rain.B)在“be+形容词”之后。

例如:He was not sure whether/if it is right or wrong.③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that。

10)it作形式主语①that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 doesn’t matter too much whether he’s 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。

②常以it作形式主语的句型有:—It +be+形容词(obvious、true、natural、surprising、good、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 +doesn’t 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。

被修饰的名词或代词叫先行词。

引导定语从句的关系代词有who、whom、whose、which、that等和关系副词where、when、why等。

关系代词和关系副词在定语从句中担任句子成分。

而引导引导非限定性定语从句的关系代词有who、whom、whose、which、of which等,这些关系代词都不能省略,通常不用关系代词that。

例如:I have two sisters, who are both students.例如:This is the man who helped me. They have a dog whose barking drives me mad.I know the reason why he came late. This is the place where we lived for 5 years.I will never forger the day when I met Mr. Liu.The doctor whom you are looking for is in the room.注意→先行词表示地点时,有时用where,有时用that引导定语从句。

这时要根据从句的谓语动词是及物的还是不及物的,是及物的就用that(which),否则就用where。

例如;This is the house where he lived last year.This is the house that (which) he visited last year.关系代词which、who或that在限定性定语从句中作宾语时可省略。

例如:Amsterdam is the place we like most.They are looking for a person (who) they can rely on.在定语从句中,若先行词指人,其关系代词可用who、whom,也可用that。

例如:The girl who/that is speaking at the meeting is our monitor.在下列情况下多用或须用who。

①关系代词在从句中作主语时。

例如:The doctor who treated me was very experienced. 给我治病的医生是很有经验的。

②先行词为all、anyone、one、ones、those、people等时。

例如:All who heard the news were excited. 所有听到这消息的人都感到兴奋。

Those who want to go please sign their names here. 想去的人请在这里签名。

④在非限制性定语从句中。

例如:Tom’s father, who is over sixty, still works hard.⑤在被分隔的定语从句中。

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