主语从句的意义是什么（看看认识有多深）

一、定义

首先主语是指动作的发起者或执行者，当一个从句在主从复合句中作主语成分时，就称之为主语从句，引导主语从句的词称之为引导词或连接词。

That Tom got the first place in the class made Linda happy. Tom获得班上第一名，让Linda很开心。(Tom got the first place 为主语从句，That为引导词)

二、引导词/连接词

(一)that(that在主语从句中只起连接作用，无实际意义，不作成分)

1.that主语从句放句首(这类主语从句中，that不能省略)

That Tom will go home on National Day makes his parents happy. Tom国庆节回家，这让他父母感到很开心。(That引导主语从句Tom will go home on National Day )

2.that主语从句后置(这类主语从句中，it作形式主语，真正主语是that引导的主语从句，此时that一般也不能省略，非正式有时会出现省略)

①It suddenly occurs to Tom that he forgot to feed the cat. Tom突然想起他忘记喂猫了。(it作形式主语，真正主语是that引导的主语从句he forgot to feed the cat)

②It is important that we learn English well. 学好英语是很重要的。(it作形式主语，真正主语是that引导的主语从句we learn English well)

③It is a good idea that we will go fishing tomorrow. 我们明天会去钓鱼，这是个好主意。(it作形式主语，真正主语是that引导的主语从句we will go fishing tomorrow)

④It is reported that it is going to rain tomorrow. 据报道，明天会下雨。(it作形式主语，真正主语是that引导的主语从句it is going to rain tomorrow)

(二)if/whether(if/whether在主语从句中起连接作用，翻译为"是否"，不作成分，不能省略)

1.更常用whether主语从句，放句首或后置，if主语从句只能放在it 作形式主语时的后置从句。

①Whether Linda will come to Guangzhou is not sure. Linda是否会来广州，还不确定。(whether引导主语从句Whether Linda will come to Guangzhou)

②Whether you succeed or not doesn't matter. 你是否成功并不要紧。(whether引导主语从句Whether you succeed or not)

③It is doubtful whether/if Tom will arrive here on time tomorrow. 明天Tom是否能按时到这儿，还不能确定。(it作形式主语，真正主语是whether/if引导的主语从句whether Tom will arrive here on time tomorrow)

(三)其他连接词(起连接作用，根据具体词翻译对应意思，主要作主语、宾语、表语、定语、状语)

1.连接代词: what, whatever, who, whoever, whose, which, whichever...

①What we don't have always attracts us. 我们没有的东西总是会吸引我们。(what引导主语从句What we don't have，此时what在主语从句中作宾语)

②Who will win the match is not sure. 谁将赢得比赛还不知道。(who引导主语从句Who will win the match，此时who在主语从句中作主语)

2.连接副词: why, when, whenever, where,wherever, how...

①When the train will arrive has been announced. 火车什么时候到，已经公布了。(when引导主语从句When the train will arrive，此时when在主语从句中作状语)

②Whenever you come is welcomed. 随时欢迎你来。(whenever引导主语从句Whenever you come，此时whenever在主语从句中作状语)

三、注意点

主语从句与宾语从句举例区分易混淆点

1.it形式主语/形式宾语

①It is necessary that we should learn English well. 我们学好英语是必要的。(it作形式主语，真正主语是that引导的主语从句we should learn English well)

②Tom thinks it necessary that we should learn English well. Tom认为我们学好英语是必要的。(it作形式宾语，真正宾语是that引导的宾语从句we should learn English well)

2.whether是否

①Whether Linda will go shopping with me tomorrow is not sure. Linda明天是否会和我一起去购物，还不确定。(whether引导主语从句Whether Linda will go shopping with me tomorrow)

②Whether Linda will go shopping with me tomorrow, I don't know. Linda明天是否会和我一起去购物，我还不知道。(whether引导宾语从句Whether Linda will go shopping with me tomorrow)

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