1、主语从句名词性从句包括：主语从句、表语从句、宾语从句和同位语从句。引导名词性从句的连词有：A.连词：that, whether, if（这三个词都不作从句的成分，同时，that无含义，而 whether 和 if 都表“是否”）B.疑问代词：who, whom, whose, what, whichC.疑问副词：when, where, why, how（一）主语从句：在复合句中充当主语的从句。1.that 引导主语从句that 引导主语从句时不同于其他的连词，既无词义也不作成分，只起单纯的连接作用，且通常不可以省。为了强调 that 引导的主语从句而置之于句首时，that 不可省。That
2、the driver could not control his car was obvious. 很明显司机不能控制住他的车了That she was chosen made us very happy. 她被选上让我们很高兴That he will come is certain. 他要来已经千真万确了通常，that 引导主语从句时用 it 做形式主语，把从句置于句尾，此时 that 有时可省。例如：It was obvious that the driver could not control his car. 很明显司机不能控制住他It made us very happy that
3、she was chosen. 她被选上让我们很高兴It is certain that he will come. 他要来已经千真万确了如果以 that 从句为主语的句子是疑问句，就只能用先行词 it 结构。例如：Is it certain that he will come?Is it true that he would take the risk?it 做形式主语有以下几种不同的结构：(1)It + be + 形容词+ that-从句It is likely that he will come. 他可能会来It is strange that she has ever trusted
4、him. 她相信他，真令人奇怪(2)It + be +名词+ that-从句It is common knowledge that the whale is not a fish. 鲸鱼并不是鱼，这是常识Its a pity that he should have catched the train. (3) It + be + -ed 分词 + that 从句It is said that he is a famous writer. 据说他是个著名作家It is reported that there will be a storm this afternoon. 据报道下午将有一场暴风在
5、表示建议、要求、命令等意义的被动结构中，that 从句中的谓语动词常用(should) do。（参见虚拟语气部分）It is suggested that the meeting (should) be held this afternoon. 会议被建议在下午举行It is demanded that he (should) leave at once. 他被要求立即离开(4) It + seem/happen/appear 等不及物动词 + that 从句。It seems that he is wrong. 看起来似乎他错了It appears that they are in need
6、 of help. 看起来他们需要帮助 2. whether 引导主语从句，意为“是否”，只起连接作用，不充当任何成分。（置于句首时必须用 whether 引导，置于句尾时，间或可用 if。）Whether he will win the game is not clear. 他是否会赢得比赛还不清楚。 Whether he will come is uncertain. 他是否会来还不确定It is not clear whether/if he will come.It was uncertain whether he would come.3. 连词代词 what, who, which
7、, whose 等引导的主语从句。这些连接代词作用相当于代词，在从句中担当主语、宾语、表语、定语等。What we need is more time. 我们需要的是更多时间Who was responsible for the accident is not yet clear. 谁应该对这场事故负责还不清楚。Whose book it is not important. 这是谁的书并不重要。Which school you want to go matters much. 你想去哪所学校很重要4.连接副词 when, where, why, how 引导的主语从句。这些连接副词相当于副词，
8、在从句中充当状语。Why he did this is not known. 他为什么做这件事还不知道。When he will come is still unknown. 他什么时候来还不知道。It is not known why he did this. 他为什么做这件事还不知道注意：wh-引导的主语从句也常用 it 作形式主语。5.也可用 whatever,whoever,whomever,whenever,wherever 等词引导主语从句，表示“无论什么”、“无论谁”、“无论何时”、“无论在（到）哪里”等。Whatever he gave you should be handed in. 他无论给你什么都要上交Whoever told you that was lying. 无论谁告诉你，那都是撒谎Whoever comes is welcome. 无论谁来都是欢迎的
