語法是英語學(xué)習(xí)的基礎(chǔ)，英語沖刺復(fù)習(xí)，有哪些重點(diǎn)語法需要大家關(guān)注呢?
It分為兩種情況，一種是指代性it,另一種則為非指代性it。在此為大家介紹it的幾種用法。
指代性it一般是指人稱代詞it， it作人稱代詞時(shí)可指代事物、動(dòng)物、嬰兒、未知的人或一件事。
例句1：It’s a theory to which many economists subscribe, but in practice it often leaves railroads in the position of determining which companies will flourish and which will fail. 這句話中第二個(gè)it就是指代前面的theory。這是一個(gè)許多經(jīng)濟(jì)學(xué)家贊同的理論，但是在實(shí)際中，它往往會(huì)使得鐵路處于一個(gè)決定哪些公司會(huì)興旺，哪些公司會(huì)衰敗的地位中。
例句2： Until these issues are resolved, a technology of behavior will continue to be rejected, and with it possibly the only way to solve our problems. 在這句話中，it指代a technology of behavior will continue to be rejected 這一情況。除非這些問題得到解決，研究行為的技術(shù)手段就會(huì)繼續(xù)受到排斥，解決問題的唯一方法也可能隨之受到排斥。
第二種情況是非指代性it。非指代性it是相對于作人稱代詞的it而言的。他們往往沒有具體意義上的主語，它用于表示氣候、溫度、時(shí)間、地點(diǎn)、距離等。非指代性it常作seem, appear, look, happen, occur, follow等動(dòng)詞的主語，構(gòu)成特定的句型。
例句：From an analysis of the hot-spot population it appears that the African plate is stationary and that it has not moved during the past 30 million years.這句中it沒有實(shí)際意義，為非指代性用法，that引導(dǎo)表語從句。從熱點(diǎn)人口分析中可以看出，非洲板塊是靜止不動(dòng)的，而且在過去的三百萬年中也從未移動(dòng)過。
當(dāng)然，在考研考試中，it的重難點(diǎn)更加具體和明確。
it 做先行詞。it做形式主語或者形式賓語。It作形式主語時(shí)，往往放在句首，將真正的主語(動(dòng)詞不定式、動(dòng)名詞、從句)放在之后。其中it可作形式主語指代不定式，這時(shí)常見的謂語有：take, pay, make, cost, require, feel, annoy, need等。另外，it形式主語指代It形式主語指代從句，而且主要形式為It is+a.+than; It is+n.+that; It is+done+that; It+vi+that;
例如：It is difficult to the point of impossibility for the average reader under the age of forty to imagine a time when high-quality arts criticism could be found in most big-city newspaper.
It做形式賓語是放在謂語動(dòng)詞與賓語補(bǔ)足語之間，指代不定式、動(dòng)名詞、從句等。后接it作形式賓語的謂語動(dòng)詞有：feel, consider, find, believe, make, take, imagine, suppose, think, deem, regard, count等。
引導(dǎo)強(qiáng)調(diào)句的it。同學(xué)們所熟悉的強(qiáng)調(diào)句型中，它的基本形式就是“it+be的某種形式+that/who從句”。當(dāng)被強(qiáng)調(diào)部分是人時(shí)須用who, 其他情況用that。例句：Curbs on business-method claims would be a dramatic about-face, because it was the Federal Circuit itself that introduced such patents with its 1998 decision in the so-called State Street Bank case, approving a patent on a way of pooling mutual-fund assets. 在because從句中就運(yùn)用了it was ….that的強(qiáng)調(diào)句型，強(qiáng)調(diào)部分為the Federal Circuit itself. 對商業(yè)方法專利申請的限制將會(huì)是一個(gè)巨大的改變，因?yàn)檫@些專利正是聯(lián)邦巡回法院自己在1998年審理一個(gè)被稱作“美國道富銀行”的案件時(shí)提出的，判決中巡回法院批準(zhǔn)了一項(xiàng)共同基金資產(chǎn)集資方法的專利。
it作句子的真正主語
1.it 指前面已經(jīng)提到過的人或事物，有時(shí)指心目中的或成為問題的人或事物，作真正主語。
例如：
What’s this? -It is a sheep? 這是什么??這是一只綿羊。
Who is it? -It’s me (I). 誰??是我。
It’s the wind shaking the window. 是風(fēng)刮得窗戶響。
2.it指時(shí)間、季節(jié)。一般用在無人稱動(dòng)詞的主語。
例如：
What time is it? -It’s nine. 幾點(diǎn)了??九點(diǎn)了。
It’s time for the meeting. Let’s go. 開會(huì)的時(shí)間到了，我們走吧。
What day is today? -It’s Saturday. 今天星期幾??今天星期六。
What’s the date today? -It is October 1st.
今天是幾號? ?今天是十月一日。
What season is it? -It is summer. 現(xiàn)在是什么季節(jié)??是夏季。
3.it 指氣候。一般作無人稱動(dòng)詞的主語。
例如：
Is it cold in this room? -No, it isn’t. 屋里冷嗎??不冷。
What’s the weather like today? -It is fine.
今天天氣怎么樣??是晴天。
It often rains in summer and it often snows in winter in this city.
這個(gè)城市夏天經(jīng)常下雨，冬天經(jīng)常下雪。
4.it指距離、情況等。一般用作無人稱動(dòng)詞的主語。
例如：
It is five kilometers from my home to the school.
從我家到學(xué)校有五公里。
It is very near from this factory to that one.
從這個(gè)工廠到那個(gè)工廠非常近。
It is a long way to the sea. 離海很遠(yuǎn)。
Is it well with you? 你身體好嗎?
it作形式主語
動(dòng)詞不定式、動(dòng)名詞短語起、從句在句子中起主語作用，而這一部分用詞較多時(shí)，可以用it作為形式主語，放在句首代表其后所說的事實(shí)上的、真正的主語，而把真正的主語放在后面。
1.It +謂語+動(dòng)詞不定式。It 作形式主語，動(dòng)詞不定式作真正的主語。
例如：
It is difficult to climb a mountain. 爬山是很艱難的。
It’s a good habit to do morning exercises. 作早操是個(gè)好習(xí)慣。
It’s important to do proper memory work in the study of a foreign language. 在學(xué)習(xí)外語時(shí)適當(dāng)?shù)刈鲆恍┯兄谟洃浀木毩?xí)是很重要的。
It is right to do so. 這樣做是對的。
2.It+謂語+動(dòng)名詞短語。It 作形式主語，動(dòng)名詞短語作真正的主語。
例如：
It is dangerous playing with fire. 玩火是危險(xiǎn)的。
It is no use learning without thinking. 學(xué)而不思則罔。
It’s useless arguing with a silly boy. 和笨孩子爭論是沒有用的。
3.It +謂語+名詞性從句。It 作形式主語，以that 引導(dǎo)的名詞性從句是真正的主語。
例如：
It is a pity that you didn’t see such a good film.
你沒看這么好的電影，真可惜。
It is certain that we shall succeed. 我們一定會(huì)成功。
It is strange that nobody knows where he lives.
真奇怪，誰也不知道他住在哪里。
(It is strange that…后面可用虛擬語氣。
如：It is strange that he should have made such a mistake.
他居然犯了這樣一個(gè)錯(cuò)誤，真奇怪。
It is strange that nobody should know where he lives.
居然沒有人知道他住在哪里，真奇怪。)
It is said that the plane will take off at ten tomorrow morning.
據(jù)說飛機(jī)明天上午十點(diǎn)起飛。
it 用于強(qiáng)調(diào)結(jié)構(gòu)
在表示強(qiáng)調(diào)的結(jié)構(gòu)中，it 可用作先行代詞，這種結(jié)構(gòu)的句型如下：It +is/was +被強(qiáng)調(diào)的部分+that +其他部分。如果強(qiáng)調(diào)的部分是人，可用who, whom 代替that.
例如：
Professor Wang teaches us English every Monday afternoon.
王教授每星期一下午教我們英語。
強(qiáng)調(diào)主語：It is Professor Wang who teaches us English every Monday afternoon.
強(qiáng)調(diào)間接賓語：It is us whom Prof. Wang teaches English every Monday afternoon.
強(qiáng)調(diào)直接賓語：It is English that Prof. Wang teaches us every Monday afternoon.
強(qiáng)調(diào)狀語：It is every Monday afternoon that Prof. Wang teaches us English.
It was here that I first met him. 這就是我初次與他見面的地方。
(強(qiáng)調(diào)狀語)
It is the people who are realy powerful.
翻譯練習(xí)
1)該上課了，快。
It is time for class. Hurry up.
2)從這兒到你們學(xué)校遠(yuǎn)嗎??不遠(yuǎn)，大約一公里。
Is it far from here to your school? ?No, it isn’t. It’s about a kilometer.
3)從我家到頤和園去很近。
It is very near from my home to the Summer Palace.