一. 基本用法1. 用作人称代词，代替上文提到过的事物，或事物（同名同物）。
The train has arrived. It arrived half an hour ago. I have a car, so you can borrow it. one 指代单数可数名词，同名异物。
He has an MP4, but I will buy one tomorrow. that特指单数可数名词或不可数名词。
The population of China is larger than that of Japan. The weather of Chongqing is hotter than that of Beijing.2. 用来代替提示代词this, that。
—What’s this?—It’s a knife. —Whose watch is that?—It’s mine.3. 指代不明性别的人。
—Who is knocking at the door? —It’s me. It is a baby.4. 指环境情况、时间、日期、天气、温度、季节、距离、价格、速度等。
It was very noisy at the very moment. —What time is it? —It’s eight o’clock. It often rains in summer here. It is a long way to the school. It is 29 ℃ today. It is five kilometers away.5. 作形式主语。
It is not easy to finish the work in two days. It is no use helping him solve the problem. It isa pity that you didn’t read the book.6. 作形式宾语。
I think it no use arguing with him. I found it very interesting to study English. He made it clear that he was not interested in that subject.7. 用于强调结构。
①It is/was + 被强调部分+ that/who + 原句剩余部分It was Xiaoming whom(that)I met in the street last night. It was in the street that I met Xiaoming last night. It ws last night that I met Xiaoming in the street. It was I who met Xiaoming in the street last night. Was it in the street that you met her? ②特殊疑问词+is/was+it+that+原句剩余部分Who was it that broke the window? What is it that you want me to do? Where was it that he bought the bike?③对until进行强调要把not放在前面。
It was not until yesterday that I met my old friend.It was not until he told me that I knew it.④对as,since引导的原因状语从句，要把as,since变成because.It was becaude he got up late that he missed the first bus.⑤判断是否是强调句的方法：It is/was…that/who去掉，看句子是否完整，完整的是强调句。
It is there that accidents often happen. It is clear that not all the boys like football. ⑥注意强调句与主语从句、定语从句、状语从句的区别It is a good idea that occurs to me suddenly（强调句）. It is a good idea that we play basketbll after school(主语从句). It is in a small factory that my brother is going to work（强调句）. It is a small factory where my brother is going to work.（定语从句）It wa s five o’clock when the plane landed at the airport(状语从句). It was at five o’clock that the plane landed at the airport（强调句）.二. 含有it的句型1.It is time (for sb.) to do sth. It is high/about time that sb. did/should do sth.(虚拟语气) It is time for us to have a rest. It is high time that we took/should take action. It’s about time that we went to the airport.2. It is + adj. +of / for sb. + to do sth. 形容词为brave, clever, careful, hopeless, kind, good, naughty, nice, silly,stupid,foolish, wise等对人的品质或性格进行评价的词, 一般用 of. It is very kind of you to help me.3. It is + adj. + that + sb. + (should) do sth.（虚拟语气）, 能用于这个句型的形容词有strange, wonderful, natural, good、proper, right, wrong, well, fortunate, important, necessary, useless, likely, probable, impossible等, 可省去should而直接用动词原形。
如：It is important that we should pay close attention to grain. It is natural that he（should）say so.4. It is no use/ good + doing sth. It is no use trying again. It is no good arguing with your leaders.5. It is said/reported/announced/ (well) known … that… It is said that he does well in English.6. It is/was +一段时间+ since … It is three years since I met him in Beijing. It is a long time since I lived in that small mountain village with these farmers.It is five months since I arrived in New York. It is five months since I was in New York.7.It will be+一段时间+ before …主句的时态可用一般将来时或一般过去时。
It will be several years before we meet again. It was not long before they set out for the front.8. It is /was/will be the first/second/third … time that … It is the first ti me that I have been here.It was the second time that he had seen the film.9.It is up to sb. to do sth … 应由某人做某事。
It is up to you to decide whether we start or not.10. sb. hate/like/dislike/love/enjoy/resent/appreciate/don’t mind/be fond of/feel like/see to等+it+宾语从句。
I hate it that you can swim so well. I enjoy it when you help someone who is in trouble.11. It takes sb. some time/ some money to do sth. It took him five years to draw a horse well.12. 主语+vt.+it+n./adj.+to do sth. I think it hard for you to do the task on you own.13. 主语+vt.+it+n./adj.+宾语从句。
I think it important that you should attend the meeting.1. It was 8 o’ clock____ it began to rain. A. that B. while C. when D. since2. It was at 8 o’ clock____ it began to rain. A. t hat B. while C. when D. since3. It was in the hall ____ we have dinner ____ we had a dancing party.A. which; whereB. that; whereC. where; whichD. where; that4. It is only when you nearly lose someone ____ you fully realize how much you value him.A. doB. thenC. thatD. who5. It will be a long time ____ Frank ____ back from abroad.A. before; comesB. since; has comeC. when; will comeD. after; will6. —It’s a long time ____ I saw you last. —Yes, but it won’t be a long time ____ we meet again.A. that; untilB. since; beforeC. when; thatD. before; since7. It was at the school ____ was named after a hero ____ he spent his childhood.A. which; thatB. where; whereC. that; whereD. which; where8. It is the first time that the professor has been to the United States, ____?A. isn’t heB. hasn’t heC. isn’t itD. hasn’t it9. It was ____ who cheated her out of money. A. his B. him C. them D. they10. How long is it ____ you became a member of the golf club? A. since B. before C. when D. that11. It’s time we ____ wasting our time doing nothing.A. will stopB. stoppedC. are going to stopD. must stop12. It was for the first time in my life ____I ____ given such a beautiful present.A .since; was B. that; was C. that; had been D. before; was13. It is not what you expect to receive but what you are ready to give ____ counts in love.A. whichB. whatC. thatD. it14. ____it is what you’ve found, you must give it back to the person it belongs to.A. ThatB. WhatC. WhateverD. However15. Where ____ you saw him last week? A. was it that B. was that C. was it D. that it was16. Is ____ necessary to complete the design before National Day? A.this B.that C.it D.he17. I don't think ____ possible to master a foreign language without much memory work.A.thisB.thatC.itsD.it18. Does _____ matter if he can't finish the job on time? A.this B.that C.he D.it19. It was not _____ she took off her glasses _____ I realized she was a famous film star.A.when; thatB. that; untilC.until; thatD.when; then20. I was disappointed with the film. I had expected _____ to be much better. A.that B.this C.one D.it21. _____is a fact that English is being accepted as an international language. A.There B.This C.That D.It22. — Do you like ______ here?— Oh, yes. The air, the weather, the way of life. Everything is so fine.A. thisB. theseC. thatD. it23. I like _____ in the autumn when the weather is clear and bright. A. this B. that C. it D. one24. The young lady at the corner was holding a baby in her arms and _____was crying for some more milk.A. itB. oneC. sheD. who25. Mr. Green kept telling her daughter not to surf the Internet too frequently, but _____ didn’t help.A. heB. sheC. whichD. it26. I want to know ____: Has Mr. Jones been here the whole morning? A. it B. one C. that D. this27. The pacific region will be one of the fastest areas in the world in the 21st century. _____ shouldn’t beany doubt about it now. A. It B. That C. This D. There28. It is _____of you to cheat in the exam. A. dangerous B. difficult C. foolish D. kind29. It took us over an hour______ along the street. A. walk B. to walk C. walking D. walked30. Nothing is wrong with the radio, _____? A. isn’t it B. is that C. is it D. isn’t that31. It’s the third time you _____ late this week. A. arrive B. arrived C. have arrived D. had arrived32. — He was nearly drowned once. — When was ______?— ______ was in 1998 when he was in middle school.A. that; ItB. this; ThisC. this; ItD. that; This33. Let's get through the work quickly.____seems to be little time left now. A. It B. That C. There D. We34. She was glad that success would ____for the women who would follow.A. make things easierB. make it easierC. be easierD. be easier to make35. I've already forgotten ____ you put the dictionary.A. that it was whereB. where it was thatC. where was it thatD. that was it that。