名词性从句重难点精讲

　　名词性从句就是在句子中起名词作用的从句。根据这种从句在句子中所充当的语法成分,又可分为主语从句,宾语从句,表语从句和同位语从句。我们学过的状语从句(又叫副词性从句)和定语从句(又叫形容词性从句)也是根据这些从句的句法功能而命名的。例如:

What he said is not true.（主语从句）

I don’t trust what he said.（宾语从句）

Such is what he said.（表语从句）

The news that he was praised is not true.（同位语从句）

It was raining when we got there.（状语从句）

The news that he gave us is not true.（定语从句）

1.名词性从句的引导词

总的来说,名词性从句的引导词可分为三类(见下表)

连接词		在名词性从句中的用法示例				要点提示
		主语从句	宾语从句	表语从句	同位语从句
一	that	That he left is certain.	I knew (that) he had left.	The fact is that he left.	I've no idea that he left.	that没有意义，在从句中也不做任何成分，只起引导作用。
二	whether/if/as if/because/as	Whether he left (or not) is unknown.	I know who left.	My question is who left.	I have a question about who left.	有一定的词义，但不在从句中作语法成分。as if/because/as只引导标语从句。
三	关系代词：who, what, which, whose等以及加-ever构成的词	Who left is unknown.	I know who left.	My question is who left.	I have a question about who left.	既有一定的语义、宾语、定语等成分。
	关系副词：how, why, when, where等以及加-ever构成的词	When he left is unknown.	I'm uncertain when he left.	What I wonder is when he left.	I have no idea when he left.	既有一定的语义，又在从句中做状语。

 

2.引导名词从句的that和引导定语从句的that用法有何不同?

主要的差异有以下几点:

▲引导名词性从句的that没有语义,只起引导词的作用;引导定语从句的that指代先行词,有一定的语义。

That he was punished by his parents was a surprise.(名词性从句)

All that I can do is to wait.(定语从句)

▲that 在名词性从句中不做任何语法成分,但在定语从句中可充当主语、宾语等。

That the 2000 Olympic Games will be held in Sydney is well known.

The book （that） he is looking for just under his nose. （that  在定语从句中作look for 的宾语）

▲that 引导主语从句和同位语从句时不可省略,引导宾语从句和表语从句一般可以省略。引导定语从句的that在定语从句中作宾语时通常可以省略。

It is important that we should be there on time.

Everything （that）he has are gone.

3.whether 和if 均可引导名词性从句,用法有什么不同?

whether可以引导所有的名词性从句, if 只能引导宾语从句和位于句尾的主语从句。注意下列特殊情况。

▲表语从句和同位语从句中只能用whether:The question is whether the film is worth seeing./ The news whether our team has won the match is unknown.

▲whether引导的主语从句可位于句首、句末,if 引导的主语从句只能位于句末:Whether we shall attend the meeting hasn’t been decided yet.

▲若宾语从句或位于句末的主语从句含有 or not与引导词直接连用时,只能用whether:We didn’t know whether or not she was ready.

▲whether 后可直接跟不定式,if 不能:He doesn’t know whether to stay or not.

▲whether引导的从句能做介词的宾语(介词常省略),if不能 :It all depends （on） whether they will support us.

▲动词wonder 后的宾语从句用 whether或if引导,而不用that引导。肯定式的 doubt 后可接 whether或if 引导的定语从句,否定式 doubt 后的宾语从句须用 that引导:I doubt whether he will come soon./ I do not doubt that he will come soon./ Do you doubt that he will come soon?

▲用if容易引起歧义时应换用whether:Please tell me if you like it.(请告诉我你是否喜欢它或如果你喜欢它就告诉我)

4.使用关系代词引导名词性从句时有哪些注意事项?

使用关系代词引导名词性从句时首先要清楚各个关系代词的语义以及它们相应的用法。具体有以下几点:

▲what指无限定范围的选择。若已限定了范围,则应用which。

 That is what he chose.

 Which team has won the game is not known yet.

▲what （ever），whoever， whichever 等是双重关系代词,它既起先行词的作用,又起关系代词的作用,此时不可在这些词前加that， all或在这些词后再加关系代词。

（×）All what she said is true. （可说All that she said is true. 或 What she said is true）

（×） Whatever that is worth doing should be done well. (应去掉that)

（×） The gold medal will be presented to whoever that comes out first. （应去掉that）

▲表示“不论谁”之义时,应用whoever,不可用who。

（×） Who has helped to save the drowning girl is worth praising.（改 who 为 whoever，或 anyone who ）（比较:Who will attend the meeting is not decided.）

5.使用关系副词应注意哪些事项?

常见的关系副词有 when（ever），where（ever）， why（ever），how（ever）等,这些词既是引导词,有在从句中作状语。需要注意的是,how可引导名词性从句,但不可引导定语从句。

The question is how we can get the loan.

（×） I don’t like the way how he spoke to her. （ 应去掉how 或将其改为that 或 in which）

6.使用主语从句应注意哪些问题?

有以下问题要注意:

▲除上面提到的if 引导的主语从句不可位于句首外,下列情况中的主语从句也不可位于句首。

①It doesn’t matter+how （whether....）主语从句中的主语从句

（×）Whether he likes it or not doesn’t matter. （应说It doesn’t matter whether he likes it or not）

②It’s said （reported， announced ... ）+主语从句中的主语从句

（×）That the highway will be open to traffic next year is said. （应说: It’s said that the highway will be open to traffic next year.）

③It happens （occurs ... ）+主语从句中的主语从句

（×）That she had forgotten to lock the door occurred to her. （应说: It occurred to her that she had forgotten to lock the door）

④含主语从句的复合句是疑问句时

  （×）Is that it will snow in the afternoon likely?  （ 应说:Is it likely that it will snow in the afternoon? ）

▲下面两个句型习惯上使用it作形式主语。

①It is a pity （a fact， a shame， an honor ... 等名词）+that 从句
It is a pity that you didn’t attend the meeting.

②It is natural （obvious，possible，unlikely，strange...等形容词） + that 从句。

It is strange that he didn’t come to school.

▲需要注意的是,当 what作“……的东西”讲引导主语从句时,一般不用it作形式主语。whatever， whoever， whichever引导的主语从句一般不用it作形式主语。

（×）It is more experience what he needs. （ 应说:What he needs is more experience.）

▲注意辨别it作形式主语与it引导的强调句型的差异。如果把句中的it is/ was ... that/ who ...去掉,剩余部分仍能组成一个意义和结构均完整的句子,则原句是强调句型。

It was last summer that he graduated from the college.（→He graduated from the college last summer.） （强调句型）

It is a shame that he didn’t pass the exam  （主语从句）

7.使用宾语从句应注意哪些事项?

能跟宾语从句的词有动词、介词和形容词。使用宾语从句时要注意宾语从句与这些词的搭配关系。

▲admit，agree，answer，believe，decide，don’t doubt，expect，ex-plain，hear，feel，hope，imagine，intend，insist，mean，notice， remember， request，require，say，see，suggest，think，wish 等动词后常跟 that 引导的宾语从句。在  advise，ask，discover，discuss，doubt，find out，imagine， inform，inquire，know，question，tell，wonder (想知道)等动词后常跟 what, whether （if）引导的宾语从句。

I remember that I have seen her somewhere in the past.

I don’t know what she has bought for father’s birthday.

▲advise， ask， inform， question， teach， tell 等动词后习惯跟间接宾语+宾语从句(间接宾语有时可省略)。

He has informed me when they are to discuss my suggestion.  

注意:repeat， announce， explain， describe， say， point out等后的间接宾语前须有to。

You can say to him exactly what you think.

▲有些词如hate， see to， take（认为）等后习惯上跟一个形式宾语it再接宾语从句。

I hate it when people talk with their mouths full.

I shall see to it that he is taken good care of when you are absent.

I take it that you should rewrite the paper.

▲当动词跟宾语从句再跟宾补时,须用it作形式宾语,而将宾语从句移至宾语补足语之后。

He has made it clear that he won’t agree to the plan.

I heard it said that she had gone abroad.

▲ allow， dislike， refuse， like， love， force， admire 等动词不可接that 从句作宾语(可用不定式或-ing 形式表示)。

（×） I admire that they won the match.（可说:I admire their win-ning the match）

▲envy， order， advise， congratulate 等之后不可用从句作直接宾语。

(×)I envy him that he is so successful. （可说:I envy his being so successful ）

▲引导宾语从句that的通常可以省略,但agree， argue， learn， observe， suggest， announce等动词后的宾语从句的that通常不可省略。

▲形容词 afraid， anxious， certain， glad， proud， determined， surprised， worried， sorry， sure， thankful， ashamed， disappointed， pleased， satisfied， content等之后可跟宾语从句。

I’m not sure whether （if） we can persuade him not to smoke.

▲介词后也可跟宾语从句。 in， but， except 后习惯上用 that 引导宾语从句。

Whether we can succeed depends on how well we coorperate.

▲主句谓语动词是 think， consider， suppose， believe， except， guess， imagine 等表示“认为,相信,猜测”的动词时,习惯上把否定词放在主句谓语上,但否定的是从句。

I don’t think he can do it better than I. 我想他不会比我干得更好。

8.使用表语从句应注意哪些问题?

使用表语从句应注意以下几点:

▲能接表语从句的联系动词除be外,还有look(看起来),ap-pear， remain， seem等。

It appears （to me） that she was wrong.(在我看来)她似乎错了。

▲引导表语从句的that常可省略。

▲当主语是the reason时,表语从句要用that引导,此时不可受汉语影响而使用because.

（×） They reason why （that） he was dismissed is because he was careless and lazy. (应把because 改为 that)

▲除that， whether， how， why 等引导词外, as if/though， as， because 也可引导表语从句。

This is because two thirds of the earth’s surface is made up of vast oceans.

It seems as if it is going to snow.

9.使用同位语从句应注意哪些问题?

▲能跟同位语从句的通常是抽象名词,常见的有fact， idea， hope， doubt， news， conclusion， suggestion， problem， order， answer， decision， discovery， explanation， information， knowledge， opinion， truth， promise， report， thought等,同位语从句用于说明这些名词的具体内容。

I have no idea what has happened to him.我不知道他发生了什么事。

The news came that the war broke out.消息传来,战争爆发了。

▲注意辨别同位语从句和定语从句。

同位语从句说明其所修饰名词的具体内容,定语从句对先行词进行限制、修饰。

The suggestion that we should learn English well is very important for us. (同位语从句)

The suggestion that Mr. Lee gave is very important for us.  （定语从句）

引导定语从句的that既替代先行词,又在从句中充当一定的语法成分(主语或宾语);引导同位语从句的that只起连接作用,不在从句中充当任何语法成分。

▲除that可引导同位语从句外,关系代词和关系副词也可引导同位语从句,要注意正确选用引导词。

（×）His delay is due to the fact which the car broke down halfway.（应将which改为that）