性别不明的小孩或未知的人；指代未指明但谈话双方都知道的那件事；指代时间、天气、气候、距离等自然现象…… 二、It用作形式主语
替代作主语的从句、动词不定式、动名词，而把真正作主语的从句、动词不定式、动名词置于句尾。
It 作形式主语的常见句型：
1. 代作主语的动词不定式，其句型为 (1) It be adj. (for sb.) to do sth.
此处adj. 通常为描述事件的形容词：easy, difficult, hard, necessary, unnecessary, possible, impossible, likely, unlikely, right, wrong, important, unimportant, legal, illegal, well-mannered, ill-mannered, polite, impolite, clear, obvious, certain, suitable, proper, fit, useful, useless, dangerous…
例 It is illegal (for a teenager) to drive a car without a license. (2) It be adj. of sb. to do sth.
此处adj. 通常为描述人的形容词：kind, unkind, nice, rude, cruel, considerate, thoughtful, thoughtless, careful, careless, silly, foolish, stupid, clever, wise, crazy. 例 It's kind of you to help me with the problem. (3) It替代作主语的动名词的常见句型 It's no good/use doing… It's (well)worth doing…
It's (well)worth one's while doing/to do… It's (well)worth while doing/ to do 例 It's no use crying over spilt milk. 2. It替代作主语的从句常见句型 (1) It is + noun +从句
例 It is no secret that the president wants to have a second term at office. (2) It is adj. +clause
It's surprising that… (should)………竟然……
It's a pity/shame that…(should)………竟然……
例 It's important that you should apologize to her for your rudeness.(=It's of much importance that you should apologize to her for your rudeness.) (3) It verb sb. + clause= It is v-ing + clause
It+surprise/delight/interest/disappoint/worry/disturb/annoy/amaze /bother/concern/frighten/please/anger sb. that…
例 It worried me that she drove so fast.(= It was worrying that she drove so fast.) (4) It verb (to sb.) that…= sb/sth verb to do
(verb = appear, seem, e about, emerge, follow, chance, happen, occur, transpire, turn out , work out)
例 It (so) happened/chanced that they were out.(= They happened/chanced to be out.) (5) It is v-ed that…=sb/sth is to do
(verb=say, report, think, believe, hope, expect, agree, accept, decide, determine, intend, plan, understand, know）
例 It is said that the couple have gotten divorced.(=The couple are said to have gotten divorced.)
(6) It is v-ed that … (should)…
(verb=demand, request, require, order, suggest, advise, remend 例 It is suggested that they should begin with the third question. 三、It作主语的句型
1. It takes sb. … to do…(=sb takes…to do…)某人用多长时间做某事
例 It took the men a week to mend our roof.(= The men took a week to mend our roof.) 2. It's (just)(un)like sb. to do…（不）像某人做某事的风格 例 It was (just) like him to think of helping us.
3. It's (about/high) time that… should /v-ed…是该做某事的时候了 例 It's(about/high) time that we should take action.
4. It's the x-th time (that) … have v-ed…第几次做某事了 例 It's the third time that he has failed the driving test.
5. It is/has been… since …continuous v-ed(延续性动词) 某动作已有多长时间不发生了
例 It's 10 years that he lived here
6. It was(not)… before…过(不)了多长时间某动作发生了 例 It was not long before they arrived. 四、It 作形式宾语
用来替代作宾语的从句、动词不定式、动名词，而把真正作宾语的从句、动词不定式、动名词置于句尾。
It 作形式宾语的常见句型：
1. verb+ it+ adj./noun (for/of) to do/clause (verb=think, believe, suppose, consider, feel, make, keep…)
例 I think it hard for you to do the task on your own./I think it hard that you'll do the task on your own.
2. verb+it+adj./noun (one's) doing (adj.=useless/worth/worthwhile)(noun=no use/no good/worth one's while/a waste of time/money/energy/words) (verb=think, believe, suppose, consider, feel, make, keep…)
例 I'll make it worth your while telling me about his secret.
3. verb+it+ important/unimportant/necessary/unnecessary/natural/essential that … (should)…
verb+it+of much/great/no/little importance that…(should)… (verb=think, believe, suppose, consider, feel, make, keep…) 例 I think it important that you (should) attendthe conference.
4. verb + it+ as+ noun/adj.+ clause (verb=accept, regard, take, see, view)
例 The lecturer takes it as encouraging when so many students attend his lecture. 5. v. +it + prep. + that…
owe it to sb. that…把…归功于…
leave it to sb that…把…留给某人去做 take it for granted that …想当然 keep it in mind that…
例 Don't bother to arrange anything. Just leave it to me to sort out.
6. It用在不能直接跟宾语从句的动词后面，尤其是表示好恶的动词后，enjoy, like, love, dislike, resent, hate, don't mind, be fond of, feel like, see to 宾语从句紧跟it之后
例 I hate it you can swim so well and I can't.
7. It用在不能直接跟宾语从句的介词后面，宾语从句紧跟it之后（except that例外） 例 I'm for it that you will follow their advice. 五、强调句型
It is/was+被强调部分+ that(who)… 强调句型用来强调谓语动词以外的任何句子成分。当被强调部分是人时也可以用who。 在使用强调句型时需注意以下几点： 1. 请注意强调句型的特殊疑问句
例 When was it that he changed his mind to take part in the activity？ 2. 在强调原因状语从句时，只能强调由because所引导的从句 例 It was because he was ill that he didn't e to school yesterday.
3. 在强调not … until结构时必须把not与until一起放到被强调的位置上
例 It was not until she took off her dark glasses that I realized she was my brother. 4. 注意强调句型与定语从句的区别
例 It was at 7 o'clock that he came here yesterday.( 强调句型) It was 7 o'clock when he came here yesterday.(定语从句) 六、It 常用的固定搭配 1. make it
(1).在口语当中相当于succeed,表示：成功、做到、说定、赶上、及时到达 例 It's hard to make it to the top in show business.
(2).在口语中相当于fix the date for,表示“约定好时间” 例 —Shall we meet next week?
—OK. We just make it next Saturday. 2. as it is
(1).相当于in fact, in reality表示“事实上，实际情况是……”
例 We had planed to finish the task today, but as it is we probably won't finish it until next week.
(2).相当于方式状语从句，表示“照原样” 例 Leave the table as it is.
3. as it were 相当于as one might say, that is to say, 表示“也就是说，可以说，换句话说”
例 He is, as it were, a modern Sherlock Holmes.
4. if it weren't for…/if it hadn't been for…用来引导虚拟语气，相当于without, or but for, 表示“如果不是……，要不是……”
例 If it weren't for Tom, I wouldn't be alive today. 5. that's it
(1). 相当于That's all. That's so much. 表示“至此为止，没有别的了” 例 You can have one more sweet, and that's it. (2). 相当于 That's right.表示“对啦”
例 — I guess the key to the problem is thechoice “A” —That's it.
6. catch it 在口语中，相当于be punished/scolded for doing sth. wrong. 表示“因做错事而挨骂，受责备，受批评，受惩罚”
例 We'll really catch it form our teacher if we're late for class again.
7. have it
(1).相当于say, insist表示“说，主张，表明，硬说” 例 Rumour has it that they are getting divorced.
(2).相当于get to know something,表示“了解，知道，获悉” 例 I had it from John that she was going abroad.
8. have what it takes在口语中，相当于be well qualified for, 表示“具有成功的条件” 例 You can take it from me that your daughter has what it takes to be a star. 9. so it seems / appears.
10. Keep at it! (Don't give up!)相当于go on,表示“继续做，不放弃” 例 My teacher asked me to keep at it. 11. Go it! (Go on!) 拼命干, 莽撞
12. Now you have done it! (You have done sth. wrong.) 13. Now you'll catch it! (You'll be punished.)
14. As it happened, … 在口语中，相当于it's a pity that…, 表示“真不凑巧，真遗憾” 例 As it happened, they were out.
15. As it turned out,…在口语中，相当于it was found to be in the end, 表示“最后被证明是”
例 As it turned out, his statement was false.
16. Such as it is(they are) 在口语中，相当于although it may not be worth much, 表示“虽然没有多大价值”
例 You can borrow my exam notebook, such as it is.
17. Take it/things easy. 相当于Don't worry or don't hurry. 用来劝告别人，表示“不要慌，别担心，存住气”
例 Take it easy! He will do it well.
18. Take it from me.在口语中，相当于believe me what I say.表示“请相信我的话，我敢担保”
例 You can take it from me that he will make it this time.
19. For what it is worth…在口语中，相当于although I'm not sure it's of value, 表示“不管其价值如何”
例 Here is the article I promise you, for what it's worth.
20. Worth it 在口语中，相当于useful, 表示“有好处，值得做” 例 Don't hesitate about it! It's worth it. 21. Believe it or not.表示“信不信由你”
例 Believe it or not, Tom is getting married to Mary next Sunday. 22. Take it or leave it. v. 要么接受要么放弃
例 That is my last offer. You can take it or leave it. 23. It all depends/that all depends 在口语中，相当于it hasn't been decided yet, 表示“那得看情况，还没有定下来”
例 —Are you going to the countryside for holiday? —It/That all depends. 24. It's up to sb. 在口语中，相当于it's decided by sb. 表示“由……决定，由……负责，取决于……”
例 —Shall we go out for dinner? —It's up to you.
“It”用法及其句型和固定搭配专练
1. Was it during the Second World War_____ he died? A.that B.while C.in which D.then (88)
2. Is ____ necessary to plete the design before National Day? A.this B.that C.it D.he (89)
3. I don't think ____ possible to master a foreign language without much memory work. A.this B.that C.its D.it (91)
4.Does ______ matter if he can't finish the job on time? A.this B.that C.he D.it (91)
5. It was not _____ she took off her glasses _____ I realized she was a famous film star. A.when , that B.until , that C.until , that D.when , then (92)
6. I was disappointed with the film. I had expected ______ to be much better. A.that B.this C.one D.it (93)
7. It was not until 1920 ______ regular radio broadcasts began. A.while B.which C.that D.since (94)
8. ______is a fact that English is being accepted as an international language. A.There B.This C.That D.It (95)
9. It was only when I reread this poems recently _____ I began to appreciate their beauty. A.until B.that C.then D.so (97)
10. I hate_____when people talk with their mouths full. A.it B.that C.these D.them (98)
11. It is the ability to do the job _____ matters not where you e from or what you are. A.one B.that C.what D.it (2000)
12.I like ___ in the autumn when the weather is clear and bright. (2004) A. this B. that C. it D. one 13. —Do you like ___ here?
—Oh, yes. The air, the weather, the way of life. Everything is so nice.(全国卷) A. this B. These C. That D. it
14. We needed a new cupboard for the kitchen. So Peter made ___ from some wood. (全国卷) A. it B. One C. Himself D. another
15. The foreign Minister said, \北京)
A. This is B. There is C. That is D. It is
16. _____ is reported in the newspaper, talks between the two countries are making progress. (2004北京)
A. It B. As C. That D. What 17. — How often do you eat out?(2004, 天津) — ________, but usually once a week.
A. Have no idea B. It depends C. As usual D. Generally speaking 18. We wanted to get home before dark, but it didn't quite _____ as planed. (2004浙江卷) A. make out B. turn out C. go on D. e up
19. — What do you want to do next? We have half an hour until the basketball game.
高中英语语法归纳总结
