1．it用于强调句式

  it用以帮助改变句子结构，使句子的某一成份受到强调。形成“It is (was) ＋被强调部分(主语、宾语、状语)＋that(或who, whom)＋其它成份。”在这个句型中，it本身没有意义。

  It was in Shanghai that I saw the film. (强调地点状语)

  我是在上海看的这部电影。

  It was my mother that /who met Tom in the street yesterday.(强调时间状语)

  正是在昨天，我母亲在大街上遇到了汤姆。

 

2．it结构在句中的应用

(1)强调主语

  It's only I who am willing to go to the cinema.

  想去看电影的只有我。

  It is not only blind men who make such stupid mistakes.

  犯这样愚蠢的错误的不仅仅是瞎子。

(2)强调宾语

  It was her that I met yesterday.

  我昨天见到的是她。

  It was a key that I found in his pocket.

  我在他口袋里找到的是钥匙。

(3)强调状语

  It was because her mother was ill that she didn't go to work.是因为母亲病了她才没有去上班。

 

3．it结构的否定句

  It was not Olivia but her sister that I saw.

  我看见的不是奥莉维亚，而是她的妹妹。

  It was not for several years that I had an opportunity of seeing him again.

  ＝I did not have an opportunity of seeing him again for several years. )我有好几年没有机会再见到他了。

 

4．it结构的疑问句

(1)这种强调句的一般疑问句只需把is/was提前。

  Was it you that broke the window?

  是你把窗户打破了吗？

    Was it in 1937 that the Second World War broke out?

  第二次世界大战是在1937年爆发的吗？

  Is it Professor Wang who teaches you English?

  是王教授教你们英语吗？

  Was it during the Anti­Japanese War that he died?

  他是在抗日战争期间去世的吗？

(2)这种强调句的特殊疑问句，只需在一般疑问句前加

  上疑问词即可。

  Who was it that broke window？打破窗子的是谁？

  When was it that you called me yesterday?

  你昨天是什么时候打电话给我的？

  What is it that you want me to do?

  你要我做的是什么？

  How was it that you succeeded？你是怎么成功的？

  Why is it that smoking is not allowed here?

  这儿为什么不允许吸烟？

  Where was it that he bought the bike?

  他是在什么地方买到这辆自行车的？

 

5．有时可用It might be...that..., It  must have been...that...句型表示强调

  It might be his father that you're thinking of.

  你关心的可能是他父亲。

  It must have been his brother that you saw.

  你看到的想必是他的兄弟。

 

6．在现代英语中，that/whom可省略

  Was it in Nanjing(that) you first met him?

  你是在南京第一次碰到他的吗？

  It was my mother(whom) you saw the other day.

  你几天前见到的是我妈妈。

 

7．这一强调句型可用于原因状语从句，当原因状语从句是as，since引导时，应该为because引导，但结果状语从句、条件状语从句、让步状语从句等不能用于这一强调句型。

  She missed the first bus since she got up late.

  ＝It was because she got up late that she missed the first bus.她因起晚了而误了第一班车。

 

8．使用这一强调句型时，需注意否定转移

  Money can't buy everything.＝It is not everything that money can buy.

  钱不能买一切。

  He didn't go to bed until twelve o'clock last night.

  It was not until twelve o'clock last night that he went to bed.昨晚他12点才去睡觉。

  I didn't relize it until I got off the bus.＝It was not until I got off the bus that   I realized it.直到下车我才意识到这一点。

 

9．用这一强调句型时，要注意以下几点

(1)不论强调句子的哪一部分，都可用that连接句子的其余部分。

(2)被强调部分指人时，可用who取代that。

(3)如果被强调部分指人，并且作后面句中的宾语时，也可用whom代替who。

(4)that，who等常常被省略掉，特别是在口语中，在强调直接宾语或间接宾语、时间或地点状语时。

(5)如果被强调的主语为人称代词时，可用主格，也可用宾格形式。

(6)被强调部分通常不能用不定代词，除非其后还有定语。

(7)如果被强调部分在后面的句子中作定语时，要用whose引导后面的句子。

(8)在强调介词宾语时，介词常置于whom等之前(介词＋whom)，但也可把介词放在其宾语之前，或放在句末。

(9)如果强调的是主语时，that或who之后的谓语的人称和数要与被强调的主语保持一致，但在口语中的个别情况下，也可能遇到与it一致的现象。

It's me that has to give it up.我不得不将它放弃。

(10)it之后的be动词的时态通常要与that之后的谓语呼应或一致。

(11)这一句型通常不能用来强调由since，as，why，although，whereas等引导的从句。