名詞性從句分類：主語(yǔ)從句

主語(yǔ)從句通常由下列詞引導(dǎo)：

1）從屬連詞that、whether等；

2）連接代詞what、who、which、whatever、whoever、whom 、whichever等；

3) 連接副詞how、when、where、why 等。

that在句中無(wú)詞義，只起連接作用；連接代詞和連接副詞都在句中既保留自己的疑問(wèn)含義、又起連接作用，連接代詞主要作主語(yǔ)，賓語(yǔ)，表語(yǔ)，定語(yǔ)等，連接副詞在從句中作狀語(yǔ)。注：whom、who指人，what指物，whatever、whoever表示泛指意義。例如：

What he wants to tell us is not clear. 他要跟我們說(shuō)什么，還不清楚。

Who will win the match is still unknown. 誰(shuí)能贏得這場(chǎng)比賽還不得而知。

It is known to us how he became a writer. 我們都知道他是如何成為一名作家的。

Where the English evening will be held has not yet been announced. 英語(yǔ)晚會(huì)將在哪里舉行，還沒(méi)有宣布。

有時(shí)為避免句子頭重腳輕，常用形式主語(yǔ)it代替主語(yǔ)從句作形式主語(yǔ)放于句首，而把主語(yǔ)從句置于句末。主語(yǔ)從句后的謂語(yǔ)動(dòng)詞一般用單數(shù)形式。常用句型如下：

（1）It be+ 名詞 + that從句

It's a great pity that they didn't get married.

他們沒(méi)能結(jié)婚，真是令人惋惜。

It 's a good thing that you were insured.

你保了險(xiǎn)，這可是件好事。

（2）It be + 形容詞 + that從句

It's splendid that you passed your exam.

你通過(guò)考試了，真棒。

It's strange that there are no lights on.

真奇怪，沒(méi)有一盞燈是開(kāi)著的。

（3）It be + 動(dòng)詞的過(guò)去分詞+ 主語(yǔ)從句

It's said that he has been there many times.

據(jù)說(shuō)他去過(guò)那兒很多次。

（4）It + 不及物動(dòng)詞 + that 從句 [1] 

另注意在主語(yǔ)從句中用來(lái)表示驚奇、不相信、惋惜、理應(yīng)如此等語(yǔ)氣時(shí)，謂語(yǔ)動(dòng)詞要用虛擬語(yǔ)氣“(should) +do”，常用的句型有：

It is necessary (important, natural, strange, etc.) that …

It is suggested (requested, proposed, desired, etc.) that…

(5) it seems/happens+that 從句

(6)眾所周知的幾種表達(dá)方式

①It is known to us that.

②As is known to us.

③What is known to us is that.

it引導(dǎo)的強(qiáng)調(diào)句結(jié)構(gòu)：It is/was+被強(qiáng)調(diào)部分+that/who+句子其它部分。

eg:My father did the experiment in the lab yesterday evening.

強(qiáng)調(diào)主語(yǔ)：It was my father who did the experiment in the lab yesterday evening.

強(qiáng)調(diào)賓語(yǔ)：It was the experiment that my father did in the lab yesterday evening.

強(qiáng)調(diào)時(shí)間：It was yesterday evening that my father did the experiment in the lab.(注意不用when)

強(qiáng)調(diào)地點(diǎn)：It was in the lab that my father did the experiment yesterday evening.