主語從句的定義：

主語從句是指在復合句中充當主語的句子，它是名詞的拓展，屬于主語的第三個表達層次。所以，主語從句和名詞一樣通常是出現在謂語動詞的前面。

例句1：Whether he will pass the examination is still unknown.

他是否能夠通過考試仍然不知道。

例句2：What he said inspired me a lot.

他說的話讓我受到了很大的鼓舞。

主語從句的引導詞：

主語從句的引導詞與賓語從句，表語從句和同位語從句的引導詞幾乎相同（表語從句有幾個特殊引導詞除外）請參照本站文章表語從句的用法講解。以下就按照引導詞在主語從句中的意義和功能分別講解。

that引導主語從句

例句1：That youth is wholly experimental is known to us all。

眾所周知，青春就是探索的歲月。

例句2：That she finished reading an English novel surprised us all.

她讀完了一部全英文小說讓我們大吃一驚。

Whether引導主語從句

例句1：Whether she will come to the party makes no difference.

她來不來參加聚會都沒有關系。

例句2：It makes no difference whether/if she will come to the party.

她來不來參加聚會都沒有關系。

Who, what, which引導主語從句

例句1：Who will be the leader of the team has not been decided yet.

誰會成為這個隊的領頭人還沒定下來。

例句2：What the kids need is a peaceful growing environment.

孩子們需要的是一個和平的生長環境。

例句3：Which you choose has nothing to do with me.

你選擇哪一個跟我沒有任何關系。

whose, what, which引導主語從句

例句1：Whose face will flush is the liar.

誰的臉紅了誰就是騙子。

例句2：What goal you set now determines what your will gain in the future.

你現在設立什么目標決定了你將來會有什么收獲。

例句3：Which bus we should take is the first problem we have to solve now.

我們應該乘坐那輛車是我們現在首先要解決的問題。

when, where, how, why引導主語從句

例句1：Why Tony did this remained a mystery. 為什么托尼做這件事仍然是個謎。

例句2：When we will have our winter holidays is still uncertain.

我們什么時候放寒假還不確定。

例句3：How the accident happened is not clear to anyone.

這場事故是怎么發生的，誰都不清楚。

例句4：Where we shall have our party is not your business.

我們應該在哪開派對跟你沒有關系。

Wh-ever連接詞引導主語從句

例句1：Whoever has a strong will is likely to become successful.

凡是有堅強意志的人都有可能成功。

例句2：Whatever is worth doing at all is wroth doing well.

凡是值得做的事情就值得做好。

例句3：whosever book is overdue will be fined.主語從句的定義和引導詞