主语从句一、概念：在复合句中起主语作用得从句叫主语从句。

（一）连接词从属连词：that、whether；关系代词：who, what, which , whom, whose, whatever, whoever, whomever, whichever；关系副词：when, where, how, why, however, whenever, wherever等；例：What he said is true、That you don’t like him is none of my business、Whether the football game will be played depends on the weather、主语从句得时态：不受主句得时态影响与限制。

（1）______ he finished writing the composition in such a short time ______(惊讶) us all、（2）______we will go for an outing tomorrow ______（remains，remained）unknown、（3）______ will be our monitor ______(be) decided yet、（4）______we must study for ______ (be) a question of great importance、（5）______ caused the accident ______（remains，remained）unknown、（6）______ you did ______ (be)right、（7）______ watch ______(be) lost is unknown、（8）______we need ______(be) time、（9）______ we need ______(be) good doctors、小结:（1)主语从句得时态：不受主句得时态影响与限制。

（2)连词位于句首不能省略（3)主语从句大多数情况下视为三单,但也有例外,如例91、从属连词that，whether引导得主语从句。

从属连词that，whether在主语从句中得作用只就是引导主语从句，在从句中不担任成分，不能省略。

例：__________ they will go is certain、__________ she will come or not is still a question、__________ she's coming or not doesn't matter too much、2、it作形式主语引导主语从句。

如果主语从句太长，为避免句子结构头重脚轻，我们可用it作形式主语，而把主语从句放在主句谓语部分之后。

That引导得主语从句可用it代替，that 不可省略。

用作it作形式主语得结构：（1）It is/was +形容词+that 从句It’s natural that…很自然……It’s obvious that …显而易见……It’s fortunate that …幸运得就是It’s (im)possible…（不）可能……It’s unlikely that…不可能It’s strange that…奇怪得就是……（2）It is/was +名词+that 从句It’s a pity that…遗憾得就是……It’s a fact that …事实就是……It’s good news that…就是好消息……It’s a wonder that…不足为奇……It’s an honour that…非常荣幸……It’s a shame that…真就是可耻……It’s common knowledge that …就是常识…（3）It +不及物动词+that 从句It seems that…似乎……It happened that…碰巧……It appears that…瞧来……It turns out that…结果……（4）It is/was +过去分词+that 从句It’s not known that………不得而知It’s said that…据说……It’s reported that…据报道……It’s decided that…尚未决定It’s believed that…据认为……It’s announced that…据宣布……It suddenly struck me (occur to me that…我突然想到（感觉到）……（5）其她It doesn’t matter …就是无关紧要得It makes no difference …毫无区别……It is of little consequence that…无关紧要It is a pity __________ she has made such a mistake、她犯这样得错误就是令人遗憾得事。

It's strange __________ he didn't come yesterday、她昨天没来就是很奇怪得。

It is reported __________ the number of wild animals in Africa is decreasing、据报导非洲野生动物得数量正在减少。

It is said __________ there was a terrible plane crash this morning、据说今天早上有一起可怕得飞机坠毁事故。

1）主语从句在句首时，必须由连注意:接词引导，不能省略这些连接词；但就是如果用it做形式主语，而把主语从句放在句末时，从属连词that可以省略。

误：They should like each other is natural、正：That they should like each other is natural、正：It is natural that they should like each other、2)如果主语从句放在句首，不能用if引导，但就是如果用it 做形式主语，而把主语从句放在句末时，也可以用if引导、误：If Mary really heard him is really doubtful、正：It was doubtful if Mary really heard him、4) 、用于It is important / natural / necessary / impossible that、、、句型中, 主语从句应使用虚拟语气, 谓语动词用\“should + 动词原形\”得形式, should有时可以省略。

5) 在It + be+suggested/advised/ordered/requested/ insisted/required 中, that从句得谓语也应该用\“should + 动词原形\”得形式, should有时可以省略。

Does _______ matter if he can't finish the job on time ?A、this B、that C、he D、it_______ is a fact that English is being accepted as an international language、A、ThereB、ThisC、ThatD、ItIt is necessary that a college student _______ at least a foreign language、A、mastersB、should masterC、masteredD、will master_______ is known to everybody, the moon travels round the earth once every month、A、ItB、AsC、ThatD、What3、由关系代词引导得主语从句。

（1）关系代词who, what, which, whom, whose, whatever, whoever, whomever, whichever等，引导主语从句时，它们分别在从句中担任主语、宾语或定语，不能省略。

__________ leaves the room last ought to turn off the lights、走得最晚得应当关灯。

__________ you have done might do harm to other people、您得行为可能伤害别人。

__________ he said at the meeting astonished everybody present、她在会议上得发言时所有入会者吃惊。

__________ made the long distance call is not important、谁打得长途电话并不重要。

（2）what引导主语从句“……得东西/事情”时，可用来表示the thing(s)which这种意思，引导从句，表示一样东西与一件事情，这种用法得what称为关系代词型what，who，whom，which，what可以与ever构成合成词，与what一样引导从句，ever起强调作用。

这些关系词在句子中充当成分，所以不能省略。

此类主语从句不能用形式主语it引导。

__________ (=The thing which I need) is a mobile phone、我所需要得就是一部移动电话。

__________ leaves the office (=Any one who leaves the office)should tell me、无论就是谁离开办公室都应该告诉我。

4、关系副词引导得主语从句。

连接副词有when, where, why, how, however, whenever, wherever等引导主语从句时，它们在从句中担任状语，不能省略。

此类主语从句可以转换为以it作形式主语得句子。

__________ he didn't come here is not clear to anyone、她为什么没来谁也不清楚。

__________ a telephone works is a question which not everyone can answer、电话就是怎样工作得，这个问题并不就是每个人都能回答。

__________ she has gone is not known yet、她去了哪儿，还不知道。