名词性从句
主语从句、表语从句、宾语从句和同位语从句，它们在复合句中的功用相当于名词，因此称为名词性从句，在句中分别作主语、表语、宾语和同位语。 1．When he will come is still unknown. 2．I don’t know who has watered the fields. 3．The problem is that we need more money.4．Have you heard the news that our team won the game?
1． 主语从句：在复合句中作句子主语的从句。 引导词：连词that、whether;疑问代词who, what, which; 疑问副词when, where, how, why (1) 连词that（无词意）, whether(是否), 在从句中不担任句子成分，只起连接作用; whether能引导主语从句，而if不能。
That you don’t like him has nothing to do with me.
Whether John will do this experiment remains a question.（2）疑问代词who, what, which, 在从句中既作连接词又充当主语、宾语、表语、定语等。
Who will be sent abroad to further his studies is not announced.What surprised me most was that such a little girl could play the violin so well.Which school will win the prize is not known.Whose dictionary has not been found is still unknown.Whichever you take will be yours.Whoever wants this book may take it.Whatever was said here must be kept secret.(3)疑问副词when, where, how, why在从句中充当时间状语、地点状语、方式状语、原因状语
When they will start hasn’t been decided yet.Where the heroine went is not mentioned at the end of the story.How he managed to finish the composition in such a short time is still a mystery.Why he often comes here is known to us all.(4)用it作形式主语的主语从句常用的句型有： It’s said that… It is certain that…
It seems/ happens that…
It’s poible/ important/ neceary/ clear that…,该句型从句的谓语动词使用虚拟语气形式：should+动词原形。
It is neceary that we should learn some English grammar.
2.表语从句：在复合句中作句子表语的从句
引导词有that, whether, what, which, who, whom, whose, when, where, why, how, because等 （1） 引导表语从句的that不省略，that仅起连接作用，在从句中不充当任何成分，无任何意义
The impreion he makes on me is that he is a reliable person.(2) the reason后面的表语从句只能用that引导，我们学生易犯“the reason is because…”的错误
The reason why the little actre has been such a succe is that she is both clever and hard-working.(3) 在表示命令order等，建议suggestion, advice等的名词后的表语从句中，谓语动词要用虚拟语气：
should+动词原形，should可省略
His suggestion is that we (should) hold another meeting to discu the problem.(4) whether可引导表语从句，表“是否”，它在从句中不充当成分，if不能引导表语从句。
The question is whether we can rely on him.(5) 连接代词what, which, who, whom, whose除起连接作用外，还在从句中做主语、宾语、表语和定语。
That’s what he is worried about.（在从句作中宾语）
The problem is who can do the work.（在从句中作主语）
（6）连接副词when, where, why, how起连接作用外，还在从句中作状语。 That’s why I was late.That is where he was born.That is how he did it.(6) 连词because引导表语从句，只用在 That/This/It is because…结构中 That is because she often works hard.
3．宾语从句：从句在句中充当宾语的成分。宾语从句可作谓语动词的宾语，也可作介词的宾语，也可作动词不定式等非谓语动词形式的宾语，还可作某些形容词的宾语从句。 Jenny thought (that) her teacher was unfair.I’d like to know which one is your husband.I am sure (that) he won’t mind.
It all depends on whether they will support us.
4.同位语从句：一般跟在某些名词后面，用以解释或说明前面的名词的内容。经常带同位语从句的名词有fact, news, meage, doubt, poibility, idea, reason, belief, hope, thought, promise, suggestion, question等。 引导词有连词that, whether；连接代词who, which, what和连接副词where, when, why, how等 （1） that, whether只起连接作用，不在从句中作任何成分。 The idea that England stands for fish& chips…is past.There is no doubt that the price of cars will go down.The problem whether we should continue to do the experiment has been solved.(不能用if) (2)连接代词who, which, what和连接副词where, when, why, how在从句中作相应成分。 He can’t answer the question how he got the money.
The question who should go abroad requires consideration.I have no idea which one I should choose.I’ve got a pretty good idea why they left early.
The question where we should go has not been discued.I have no idea when Jack will be back. 同位语从句与定语从句的区别：
We expreed the hope (that) they had expreed.我们表达了他们曾经表达过的那种希望。（定语从句）
We expreed the hope that they would come to visit China again.我们表示希望他们再来中国访问。（同位语从句）
1） 从语法角度上看，引导同位语从句的that是连词，只起连接作用，在从句中不作任何句子成分；而引导定语从句的that是关系代词，除起连接作用外，还在从句中作主语或宾语等句子成分。
2） 从语义角度上看，同位语从句与前面的名词hope是同位关系，表示hope的内容是they would come to visit China again。因而同位语从句是名词性的，其功能是对名词作补充说明；而定语从句与它前面的名词是所属关系，表示“…的”（他们曾经表示过的），起修饰作用，因此定语从句是形容词性的，其功能是修饰先行词。
3） 同位语从句的连词that不能省略，而定语从句的关系代词that，当其在从句中作宾语中，可省略，作主语也不可省略。
I’ve heard the news that he visited our factory.I’ve heard the news that he told you the other day.
The news that the plane would take off on time made everybody happy.The news that is spreading around the airport is that a heavy storm is coming.
The suggestion that students should learn something practical is worth considering.The suggestion that they are considering is that students should learn something practical.
