1、名词性从句,在句子中起名词作用的各种从句统称为名词性从句。根据它们在句子中所起的语法作用，这类从句包括主语从句、宾语从句、表语从句和同位语从句。,主语从句,1.主语从句可以直接放在句首；也可用it作形式主语，而将从句放在句末。,When we shall have our sports meet is still a question.,It is still a question when we shall have our sports meet. (我们什么时候开运动会仍然是个问题。),常见的用it作形式主语的复合句结构：,1）It is + 名词+ that 从句It is a fac
2、t (a shame, a pity, no wonder, good news, ) that ,2）It is + 形容词+ that 从句It is necessary (strange, important, wonderful, possible, likely, ) that (虚拟),3） It is+过去分词+that 从句It is said (reported, decided, ) +that 从句,4）It +不及物动词+ that 从句It seems (happened, doesnt matter, has turned out, ) that,2、 由what引
3、导的主语从句,What I told you is true. 我告诉你的事是真的。,What I want to know is this. 我想知道的就是这个,关连词what=the thing which （that ），因此以上两个句子可以改为：,The thing which I told you is true. The thing that I want to know is this.,注：what引导的主语从句一般不用it作形式主语。,It is a book what I want. (误),What I want is a book.,3、 由that引导的主语从句,由t
4、hat引导的主语从句 ，that在主语从句中不起句子成分作用，但不能省略，这和that引导宾语从句，不起句子成分作用、可以省略不同。,That she will come tomorrow is certain. （她明天到来是肯定无疑的了。）,由that引导的主语从句大多数要放到句末 ，一般用it作形式主语，因此上句可以改为：,It is certain that she will come tomorrow.,4、 由其他连词引导的主语从句,Where she has gone is not known yet. (她到哪儿去了还不知道。),How he became a three-go
5、od student is known to us all. (他怎样成为一个三好学生是众所周知的。),Why he didnt come wasnt quite clear. （他为什么不来还不太清楚。）,1、 主语为从句时，谓语动词一般要用单数形式；但如果what引导的从句作主语，代表复数概念（常可从表语上看出）时，谓语动词则常用复数形式。,What we need is water. What we need are useful books.,2、如果带主语从句的句子是疑问式，则须 用it作形式主语。,注意事项：,Has it been announced when the plane
6、s are to take off? （飞机什么时候起飞宣布了没有？）,3、由whether及其它连词引导的主语从句放在 句首或句子后部皆可。,Whether he is coming or not doesnt matter.,It doesnt matter whether he is coming or not.,4、whether和if都可引导主语从句，但if引导的主语从句不能放在句首。,4、 Whether 能引导所有名词性从句，而且能和or（not）连用；if只能引导宾语从句，而且不能和or（not）连用。,I dont know whether (if) I should tak
7、e his advice or not. 我不知道是否要接受他的劝告。,They asked whether (=if) we would need any help. 他们问我们是否需要帮助。（引导宾语从句可通用 ）,宾语从句,宾语从句的作用相当于一个名词，它可以作动词的宾语，也可作非谓语动词、某些介词和某些形容词的宾语。,He said (that) he would call on his old teacher. (他说他要去拜访以前的老师。) 作动词宾语,I want to know what has happened to her. （我想知道她发生了什么事。）做不定式宾语,Kno
8、wing (that) it is cold today, he put on another clothes. （知道今天天气冷，他又穿了件衣服。）作现在分词宾语,I was surprised at what you said. （你讲的话使我吃惊。）作介词的宾语,Im sure that he will be at home to wait for us. (我相信他将在家等我们。)作形容词宾语,注意事项：,1、有些宾语从句前要有间接宾语。,He told me what I should read. 他告诉我应该读些什么,2.如果宾语从句后面有宾语补足语，要使用形式 宾语it，而将从句
9、放在补足语后面。,I thought it strange that he failed to call me. 我觉得奇怪：他没给我打电话。,3、在think，believe，suppose，expect等动词之后的宾语从句中，如果从句的谓语是否定含义，则不用否定形式，而将主句谓语动词变为否定形式。,I dont think you are right. 我想你是不对的。,4、在think，believe，imagine，suppose，guess，hope等动词以及Im afraid等后，可用so代替一个肯定的宾语从句，还可用not代替一个否定的宾语从句,A：Do you believe
10、it will clear up? 你以为天气会转晴吗？ B：I believe so. 我认为会这样。,I dont believe so.(或I believe not.) 我认为不会这样,5、介词的宾语从句不能由if引导，而要用whether。,表语从句,表语从句放在连系动词（be，seem，remain等）后,The question is who will go there. 问题是谁愿意去那里。,This is how I do it. 我就是这样做的,The reason was that he fell ill. 原因是他病倒了。,注意事项：,1、where, why, bec
11、ause, how等引导的从句作that is和this is的表语时，表示具体的地点、原因、方式等。,This is why we put off the meeting. 这就是我们推迟会议的原因。,That is where he will go.,That was because he fell ill. 这是因为他病倒了,2、主语是reason时，表语从句常用that，不用because。,The reason for his absence was that he was ill. 他缺席的原因是病了,3、as，as if，because有时也可引导表语从句：,Things wer
12、e not as they seemed to be. 情况并不是看上去的那个样子。,It looks as if it is (or: were) going to rain. 天看起来要下雨。,（as if引导的表语从句有时也可用虚拟语气，表示可能性小。）,4、当主句的主语是suggestion，proposal，idea，order，plan等词时，表语从句的谓语 用虚拟语气。,Johns suggestion was that we (should) go to the cinema together. 约翰的建议是我们应该一起去看电影。,同位语从句,同位语从句跟在一个名词后，对其做进
13、一步的解释：,I had no idea that you were here. 我不知道你在这儿。,The fact that he didnt attend the meeting surprised me. 他没参加会议的事实使我很吃惊,同位语从句与定语从句的区别,1、从意义上讲，前者对名词加以补充说明，后者对名词进行修饰和限定。,2.定语从句的先行词一般没有特殊性，而同位语从句前的名词往往是以下这些：,belief, fact, hope, idea, doubt, news, rumor, conclusion, evidence, suggestion, problem, orde
14、r, answer, decision, discovery, explanation, information, opinion, possibility, truth, promise, report, statement,3、从内涵山讲，前者所说明的名词与从句没有逻辑关系，后者所限定的名词是从句逻辑上的主语、宾语、表语、定语、状语等。,The news that they won the match is true. 他们比赛获胜的消息是真的,news在从句中不作任何成分，与从句没有逻辑关系。,The news that you told us yesterday is true. 你昨天给我讲的消息是真的。,news 是told 的逻辑宾语,The order when we should return hasnt reached us. 我们什么时候该返回的命令还未到 。,（order与从句没有逻辑关系）,The day when New China was founded will never be forgotten. 新中国成立的那天永远不会被忘记。 （the day在从句中作状语）,
