研究職稱英語考試歷年真題，可以發(fā)現(xiàn)it句型的重要性和使用的普遍性，根據(jù)其用法特點(diǎn)可大概歸納為20個(gè)重點(diǎn)句型，希望考生能掌握這20個(gè)句型，提高考試技能。
1. It is + 被強(qiáng)調(diào)部分 + that ……
該句型是強(qiáng)調(diào)句型。將被強(qiáng)調(diào)的部分放在前面，其它部分置于that之后。被強(qiáng)調(diào)部分可以是主語，賓語，表語或狀語。強(qiáng)調(diào)的主語如果是人，that可以由who換用。如果把這種句型結(jié)構(gòu)劃掉后，應(yīng)該是一個(gè)完整無缺的句子。這也是判斷強(qiáng)調(diào)句型與其它從句的方法。
It was about 600 years ago that the first clock with a face and an hour hand was made.
It was they that （who ) cleaned the classroom yesterday.
It was in the street that I met her father.
2. It is not until + 被強(qiáng)調(diào)部分 + that ……
該句型也是強(qiáng)調(diào)句型。主要用于強(qiáng)凋時(shí)間狀語，譯成漢語"直到……才……"，可以說是 not …… until …… 的強(qiáng)調(diào)形式。
It was not until she took off her dark glasses that I realized she was a famous film star.
= Not until she took off her dark glasses did I realize she was a famous film star.
= I didn't realize she was a famous film star until she took off her dark glasses.
3. It is clear （ obvious， true， possible， certain……) that ……
該句型中it 是形式主語，真正的主語是that 引導(dǎo)的主語從句，常譯為"清楚（顯然，真的，肯定……)" 是主語從句最常見的一種結(jié)構(gòu)。
It is very clear that he's round and tall like a tree.
= That he's round and tall like a tree is very clear.
4. It is important （ necessary， right， strange， natural……) that ……
該句型和上一個(gè)同屬一個(gè)句型。由于主句中的形容詞不同，that 后的從句中要用虛擬語氣（should + 動(dòng)詞原形)，should 可以省去。建議記住該句型中的形容詞。
It is important that we （should) learn English well.
It is necessary that he （should) remember these words.
5. It is said （reported， learned……) that ……
該句型中的it 仍是形式主語，真正主語是that 引導(dǎo)的主語從句。該結(jié)構(gòu)常譯為"據(jù)說（據(jù)報(bào)道，據(jù)悉……)".
It is said that he has come to Beijing.
It is reported that another earth satellite has been put into orbit.
6. It is suggested （ ordered …… ) that ……
該句型和上一個(gè)同屬一個(gè)句型。主句中的過去分詞是表示請(qǐng)求，建議，命令等詞時(shí)，that 后的從句要用虛擬語氣（should + 動(dòng)詞原形)，should 可以省。常譯為"據(jù)建議；有命令……)
It is suggested that the meeting （ should ) be put off.
It was ordered that we （ should ) arrive there in two hours.
7. It is a pity （ a shame …… ) that ……
該句型中，that后的從句一般用虛擬語氣（should + 動(dòng)詞原形)，should可省去。表示出乎意料，常譯為"竟然".沒有這種意義時(shí)，則不用虛擬語氣。
It is a pity that such a thing （ should ) happen in your class.
這種事竟然發(fā)生在你們班上，真是遺憾！
It is a pity that he is ill. 他生病了，真遺憾！
8. It is time （ about time ，high time ) that ……
該句型中that 后的從句應(yīng)該用虛擬語氣，值得注意的是① 常用過去時(shí)態(tài)表示虛擬。② 有時(shí)也用should + 動(dòng)詞原形，should 不能省。常譯為"是（正是)……的時(shí)侯……".
It is time that children should go to bed.
= It is time that children went to bed.
9. It is the first （ second …… ) time that ……
該句型要和上一個(gè)句型區(qū)別開來。該句型中的 that 從句不用虛擬語氣，而用完成時(shí)態(tài)。至于用什么完成時(shí)態(tài)，由主句的謂語動(dòng)詞的時(shí)態(tài)決定。如果是一般現(xiàn)在時(shí)，后面從句用現(xiàn)在完成時(shí)態(tài)；如果是一般過去時(shí)，后面從句則用過去完成時(shí)態(tài)。該結(jié)構(gòu)中 that 可以省去；it有時(shí)用 this 替換。常譯為"是第一（二)……次……".
It is the first time I have been here.
= This is the first time I have been here.
10. It is …… since ……
該句型主要用作處理瞬間動(dòng)詞的完成時(shí)，又要和表示一段時(shí)間的時(shí)間狀語連用的問題。主句中是時(shí)間作表語，其時(shí)態(tài)是現(xiàn)在時(shí)或完成時(shí)，since 引導(dǎo)的從句通常是一般過去時(shí)態(tài)，而且是瞬間動(dòng)詞。如果主句是一般過去時(shí)，從句則用過去完成時(shí)。
It is （ has been ) 5 years since his father died.
11. It is …… when ……
該句型中的 when 引導(dǎo)的是一個(gè)時(shí)間狀語從句，主句中的 it 指時(shí)間，表語由具體的時(shí)間充當(dāng)。常譯為"當(dāng)……的時(shí)候，是……".
It was 5 o'clock when he came here.
12. It be …… before ……
該句型主句中的 it 指時(shí)間， 主句中的時(shí)態(tài)常是將來一般時(shí)或過去時(shí)兩種時(shí)態(tài)。主句中的表語多是long， not long ， 3 days ， 2 weeks 等表示時(shí)間段的詞或短語。常譯為"……之后……".
It was 3 days before he went to Beijing.
It will be not long before he finishes his job.
13. It happens （seems， looks， appears ) that……
該句型中it是形式主語，that 引導(dǎo)的是主語從句，主句中的happen ， seem等詞是不及物動(dòng)詞。
It happened （ so happened ) that he met his teacher in the street. 碰巧……
It seems that he will be back in a few days. 看來……
14. It takes sb. …… to do sth.
該句型中的不定式是真正的主語，it是形式主語，句型中的直接賓語是時(shí)間。常譯為"做……要花費(fèi)某人……".
It took thousands of people many years to build the Great Wall.
15. It is no good （use ) doing sth.
該句型中的真正主語是動(dòng)名詞短語，主句中的表語可以是no good ， （ not any good ) ， no use ， （ not any use )。
It is no good learning English without speaking English.
16. It doesn't matter whether （ if ) ……
該句型中whether（if) 引導(dǎo)的從句是真正主語，該句型常譯為 "不論（是否)……沒關(guān)系……。
It doesn't matter if they are old.
17. It is kind （ of sb. ) to do sth.
該句型中的不定式短語是真正主語，如果不定式的邏輯主語是由 of引起，主句中的形容詞必須是能表示邏輯主語特征的形容詞。常見的有： bad ， brave ， careless， clever ， cruel ， foolish ， good （好心的)， honest ， horrible ， kind ， lazy ， modest ， naughty ， nice（有教養(yǎng)的)， polite， rude ， silly ， stupid ， wise ， wrong（錯(cuò)誤的)等。 這個(gè)句型可以改寫為：sb. is kind to do sth.
It is kind of you to say so.
= You are kind to say so.
18. It is necessary （ for sb. ) to do sth.
該句型與上一個(gè)同屬一個(gè)句型。如果不定式的邏輯主語是由for引起，主句中的形容詞通常是表示重要性，緊迫性，頻繁程度，難易，安全等情況的形容詞。常見的形容詞有：① important， necessary， natural ② easy ， safe ， common ， normal ， hard ， difficult ， dangerous ， unusual， rare ， impossible ， pleasant等。
在①中的形容詞作表語可以用從句改寫， 如：
It is important for her to come to the party.
= It is important that she （should ) come to the party
19. It looks （ seems ) as if ……
該句型中it無意義。 as if 引導(dǎo)一個(gè)狀語從句。常譯為，"看起來好象……"如果與事實(shí)不相符合，則用虛擬語氣。
It looks as if he is ill.（真的病了)
It looks as if he were ill. （沒有生病)
It seemed as if he were dying.
20. We think it important to learn a foreign language.
該句型中的it 作形式賓語。為了記憶方便我們可稱該句型為"6123結(jié)構(gòu)".
6指主句中常用的動(dòng)詞：think， believe， make， find， consider， feel；
1指的是形式賓語it；
2指的是賓補(bǔ)的兩種形式：形容詞或名詞；
3指的是真正賓語的三種形式：不定式短語，動(dòng)名詞短語或that引導(dǎo)的賓語從句。
We think it our duty to clean our classroom every day.
He felt it important learning English well.
They found it difficult that they would finish their work in two days.
