问题描述：
it有哪些语法需要注意
问题解答：
我来补答1.It is+被强调部分+that
该句型是强调句型，将被强调的放在前面，其他部分置于之后，强调的主语如果是人，可以用来替换，如果把这种句型结构划掉后，应该是一个完整无缺的句子，这也是判断强调句型与其他从句的方法。
It was they that (who) cleaned the classroom yesterday. It was in the street that I met her father.
It was with great joy ___he received the news that his lost daughter had been found. (2004 福建)
A. because B. which C. since D. that (D)
2. It is not until +被强调的部分+ that
该句型译成汉语“直到……才”，可以说是的强调形式。It was not until she took off her dark glasses that I realized she was a film star. =Not until she took off her dark glasses did I realize she was a film star. =I didn’t realize she was a famous film star until she took off her dark glasses.
It was ___back home after the experiment. (2004 湖北)
A. not until midnight did he go
B. until midnight that he didn’t go
C. not until midnight that he went
D. until midnight when he didn’t go (C)
3. It is clear (obvious, true, possible, certain) that….
该句型中it是形式主语，真正的主语是that引导的主语从句，常译为“清楚（显然、真的、肯定）”是主语从句最常见的结构。
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…
该句型和上一句同属一个句型。由于主句中的形容词不同，that后的从句中要用虚拟语气（should+动词原形）should 可以省去。建议记住该句型中的形容词。
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…
该句型中的it 仍是形式主语，真正的主语是that 引导的主语从句。该结构常译为“据说（据报道，据悉……）
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…
该句型和上一句属一个句型。主句中的过去分词是表示请求、建议、命令等词时，that后的从句要用虚拟语气 （should+动词原形）。可以省略，常译为“据建议；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 …
在该句型中，that后的从句一般用虚拟语气（should+动词原形），should可以省去，表示出乎意料，常译为“竟然”。没有这种意义时，则不用虚拟语气。
It is a pity that such a thing (should) happen in your class.
这种事竟然发生在你们班上，真是遗憾。
It is a pity that he is ill.
他生病了，真遗憾！
8. It is time (about time, high time) that…
该句型中that后的从句应该用虚拟语气，值得注意的是：常用过去时态表示虚拟，有时也用should+动词原形，should 不能省。常译为“是（正是）……的时候……”
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…
该句型应和上一个句型区别开来。该句型中不用虚拟语气，而用完成时态。至于用哪种完成时态，由主句的谓语动词的时态来决定。如果是一般现在时，从句用现在完成时态；如果是一般过去时，从句则用过去完成时态。该结构中that可以省去；it有时用this替换，常译为“是第一（二,…）次…”。
10. It is …since…
该句型主要用作处理瞬间动词的完成时，要和表示一段时间的时间状语连用。主句中是时间作表语，其时态是现在时和完成时，引导的从句通常是一般过去时态，而且是瞬间动词。如果主句是一般过去时，从句则用过去完成时。
It is (has been) 5 years since his father died.
It is almost five years ___we saw each other last time. (2005 北京)
A. before B. since C. after D. when(B)
11. It is …when…
该句型中的when引导的是一个时间状语从句，主句中的it指时间，表语由具体的时间充当。常译为“当……的时候，是……”
It was 5 o’clock when he came here.
12. It be…before…
该句型主句中的it指时间，主句中的时态常是一般将来时或过去时两种时态，主句中的表语多是long ,not long ,3 days, 2 weeks等表示时间段的词和短语。常译为“…之后才”，“没过……就……”
It was 3 days before he went to Beijing.
It will not be long before he finishes his job.
13. It happens (seems, looks, appears) that…
该句型中的it 是形式主语，that 引导的是主语从句，主句中的happen, seem等词是不及物动词。
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. (看来……)
The Foreign Minister said, “___our hope that the two sides will work towards peace.” (2004北京)
A. This is B. There is C. That is D. It is (D)
14. It takes sb…to do sth.
该句型中的不定式是真正的主语，是形式主语，句型中的直接宾语是时间。常译为“做……要花费某人……”
It took thousands of people many years to build the Great Wall.
15．It is no good (use) doing sth.
该句型中的真正主语是动名词短语，主句中的表语可以是 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…
该句型中的引导的从句是真正的主语，该句型译为“不论（是否）……没关系……
It doesn’t matter whether they are old.
17．It is kind (of sb) to do sth.
该句型中的不定式短语是真正主语，如果不定式的逻辑主语是由of引出，主句中的形容词必须是能表示逻辑主语的形容词。常见的有：bad, brave, careless, clever, cruel, foolish good (好心的),honest, horrible, kind, lazy, modest, naughty, nice (有教养的),polite, rude, silly, stupid ,wise ,wrong等。这个句型可以改写为sb.is kind to do sth.
It is kind of you to stay so =You are kind to say so.
18. It is necessary (for sb) to do sth
该句型与上一句统属一个句型。如果不定式的逻辑主语是由for 引出的，主句的形容词通常是表示重要性，紧迫性，频繁程度，难易，安全等情况的形容词。常见的形容词有：
Important,necessary,natural,easy,safe,common,,normal,hard,difficult,dangerous,unusual,grape, impossible, pleasant.等。
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 …
该句型中it 无意义。As if 引导一个状语从句，常译为：“看起来好像……”如果与事实不相符合，则用虚拟语气。
It looks as if he is ill. （真的病了）
It looks as if he was ill. （事实上没有生病）
It seemed as if he was dying.
20. We think it important to learn a foreign language.
该句型中的it作形式宾语。为了记忆方便我们可称该句型为“7123结构”
7指主句中的常用的动词：think, believe, make, find, consider, feel, take.
1指的是形式宾语it .
2指的是宾补的两种形式：形容词和名词
3指的是真正宾语的三种形式：不定式短语，动名词短语或that引导的宾语从句。
We think it our duty to clean our classroom every day.
XiaoLi felt it important learning English well.
They found it difficult that they would finish their work in two days.
-Do you like ____here?
-Oh, yes .The air, the weather, the way of life. Everything is so nice. (2004 全国卷二)
A. this B. these C. that D. it (D)