1. 以what等連接代詞引導(dǎo)的主語從句

What you need is more practice. 你需要的是更多的練習(xí)。

Whoever wants it may have it. 誰要都可以給他。

同類的連接代詞還有：What, who, whom, whose, which, whatever, whoever, whichever

2. 以that, whether從屬連詞引導(dǎo)的主語從句

It was strange that he had made a mistake. 真奇怪，他竟然錯了。

That we need more equipment is quite obvious. 我們需要更多的設(shè)備，這是很明顯的。

Whether he will join us won’t make too much difference.

他是否加入我們，沒有太大的差別。

3. 主語從句的引導(dǎo)詞that什么時候可以省略

當(dāng)主語從句不太長時，引導(dǎo)詞“that”可以省略

It’s clear (that) he has done his best. 很明顯他已經(jīng)盡力而為了。

It’s a wonder (that) he didn’t fail. 真奇怪，他沒有失敗。

4. 以when等連接副詞引導(dǎo)的主語從句

When they will come hasn’t been made public. 他們什么時候來還沒有公布。

Where she has gone is not known yet. 她去了哪兒，還不知道。

Why he did it will remain a puzzle for ever. 為什么他做那件事將永遠(yuǎn)是個謎團(tuán)。

5. 虛擬語氣：主語從句

形容詞為necessary, important, impossible, strange, natural, essential時，在“It + be + 形容詞或過去分詞 + 主語從句”中，主語從句要虛擬。

It is necessary that the problem (should) be discussed at once.

立刻討論這個問題很有必要。

It is strange that he (should) have so many friends. 太奇怪了，他有那么多的朋友。

6. 主語從句與強(qiáng)調(diào)句的區(qū)別

注意事項(xiàng)：

1). 在主語從句中，把It was … that去掉之后，就已經(jīng)完全不像一個句子了。

2). 在強(qiáng)調(diào)句中，把It was … that去掉之后，還基本上像個句子。

3). 主語從句有以下的引導(dǎo)詞：what, who, whom, whose, which, whatever, whoever, whichever

4). 強(qiáng)調(diào)句的引導(dǎo)詞只有：that, who。

主語從句：

It was strange that he had made a mistake. 如果把，It was … that 去掉以后，剩下strange he had made a mistake.就不算是句子了。

It is immaterial where or when he goes. 他去何處或者何時去是無關(guān)緊要的。

<><>It is said that…, 和It is reported that…這樣的結(jié)構(gòu)，后面接的是主語從句：

It is said that he’s got married. 聽說他已經(jīng)結(jié)婚了。

強(qiáng)調(diào)句：

It was she that had been wrong. 錯的是她。(強(qiáng)調(diào)主語)如果把，It was … that 去掉以后，剩下she had been wrong.還勉強(qiáng)算的上是一個句子。

It was this novel that they talked about last night. 他們昨晚談?wù)摰氖沁@部小說。(強(qiáng)調(diào)賓語)

It was in London that I first saw her. 我是在倫敦第一次見到她的。(強(qiáng)調(diào)地點(diǎn)狀語)