一、考查 it 用作形式主語(yǔ)的用法當(dāng)不定式、動(dòng)名詞、從句等用作主語(yǔ)時(shí)，為避免頭重腳輕，通常在句首使用形式主語(yǔ)it，而把真正的主語(yǔ)放在句子末尾。如：It’s no good sitting up too late. 熬夜沒(méi)有好處。

It is quite clear that he has read the book. 很顯然，他讀過(guò)這本書(shū)。

It doesn’t matter what he says. 他說(shuō)什么沒(méi)關(guān)系。

【特別提醒】注意it用作形式主語(yǔ)的三類(lèi)特殊句式：1.用作動(dòng)詞look, seem, appear, happen, occur, follow等的主語(yǔ)（后接that從句或as if從句）。如：It seems that he knows everything. 他好像什么都知道。

It （so） happened that I had no money with me. 碰巧我沒(méi)帶錢(qián)。

2.當(dāng)系表結(jié)構(gòu)后接有if 或when引出的狀語(yǔ)從句時(shí)，通常在系表結(jié)構(gòu)前使用形式主語(yǔ)表示說(shuō)話人對(duì)某情況的看法。如：It was a great surprise to me when he did a thing like that. 他這樣做使我很吃驚。

It would be a tragedy if anything went wrong. 如果出了什么事就是一個(gè)悲劇。

3.用于if it were not for… / if it hadn’t been for…（若不是因?yàn)椋Ｈ纾篒f it hadn’t been for the freezing wind they could have reached the injured man in time. 要不是有刺骨的寒風(fēng)，他們就及時(shí)趕到傷員身邊了。

二、考查 it 用作形式賓語(yǔ)的用法當(dāng)不定式、動(dòng)名詞、從句等用作賓語(yǔ)且其后跟有賓語(yǔ)補(bǔ)足語(yǔ)時(shí)，就應(yīng)在賓語(yǔ)補(bǔ)足語(yǔ)前使用形式賓語(yǔ)，而將真正的賓語(yǔ)移至句末：We found it difficult to persuade her. 我們發(fā)現(xiàn)很難說(shuō)服她。

He makes it a rule to get up before dawn. 他習(xí)慣于天亮前起床。

I think it very strange that he goes out walking almost every night. 我認(rèn)為他幾乎每晚都出去散步是很奇怪的。

【特別提醒】注意it用作形式賓語(yǔ)的三類(lèi)特殊句式：1. 動(dòng)詞+it+if / when從句當(dāng)enjoy, like, dislike, love, hate, prefer, appreciate等動(dòng)詞后需要接一個(gè)if或when引導(dǎo)的從句時(shí)，此時(shí)必須要先在動(dòng)詞后接it作形式賓語(yǔ)。如：She won’t like it if you arrive late. 她不喜歡你遲到。

He hates it when people use his bike. 他討厭別人用他的自行車(chē)。

I’d prefer it if I didn’t have to do so much work. 要是我不必做那么多工作，那就太好了。

I would appreciate it very much if you would help me with it. 如果你能幫助我做這事，我會(huì)十分感激。

2. 動(dòng)詞+介詞+it+that從句能用于此句型的主要有三個(gè)動(dòng)詞，即depend on, answer for, see to.如：You may depend on it that he will turn up in time. 你可以相信他會(huì)及時(shí)趕到的。

I can’t answer for it that the boy is honest. 我不能保證這個(gè)男孩是誠(chéng)實(shí)的。

I’ll see to it that all these letters will be sent to the post before twelve. 我將注意讓所有的信件在12點(diǎn)以前送到郵局。