一、指代物

　　it可替代動(dòng)植物與無生命的東西，它與one的區(qū)別在于one= a/an + none; it = the + n。

　　1. ---Where is my pencil case? ---Isnt it in your backpack?

　　2. ---I have a motorbike. It (= the motorbike) was bought three years ago.

　　3. As this chair is broken, I must have it (= the chair)repaired.

　　4. My father bought a pen and gave it (= the pen) to me.

　　5. You can not eat your cake and have it. 世事難兩全。

　　試比較：

　　6. I have no dictionary, so I want to buy one. (one = a dictionary)

　　7. I have a dictionary, it is over there. (it = the dictionary)

　　二、指代人

　　it可指代一個(gè)未親眼看到的、不明身份性別的、面目不詳?shù)娜耍驄雰骸和掌械娜宋锏取?/p>

　　8. --- Who is there waving to you? ---Its my friend Tom.

　　9. ---Who is crying in the room? ---Its my brother Jack.

　　10. ---Who is knocking at the door? ---It must be Kate, my classmate.

　　11. ---Who is the girl in the photo on the wall? ---Its my sister.

　　12. ---Who is it? ---Its me. (有人敲門)

　　13. ---Someone is ringing the doorbell. Go and see who it is. (敲門)

　　14. ---Oh, by the way, there is a telephone call for you. ---Who was it? (打電話)

　　15. ---Who is making so much noise? ---It must be the children.

　　16. There is a person knocking at the door. Who can it be?

　　17. Just at that time, in came a girl. It was Marks sister.

　　18. There is a young lady at the door. It is his daughter.

　　19. What a beautiful baby! Is it a boy?

　　20. A baby is lying in the cradle. It was born two months ago.

　　21. The baby cry because it is hungry.

　　22. The baby has got its first tooth.

　　注意：若身份已確定則要用人稱代詞。

　　23. There is a lady at the door. She wants to see you.

　　注意：向別人介紹某人時(shí)用this。

　　24. This is my friend, Jim.

　　三、指代前述內(nèi)容, 或者是文中的內(nèi)容

　　25. Beauty is everywhere. It makes us happy.

　　26. There is a football match tonight. It starts at six oclock in the evening.

　　27. If you remember these points, it will help you.

　　28. When we die for our motherland or the people, it is a worthy death.

　　29. You have helped me a lot. I shall never forget it.

　　30. Yang Liwei was the first Chinese to be sent up into space. It made the Chinese proud.

　　31. His mother is fifty-seven, but she doesnt look it.

　　32. Mr. Wang was ill. Have you heard it?

　　33. ---Thank you for your help? ---Dont mention it.

　　34. Although we cant see it, there is air all around us.

　　35. It would be wonderful if you could come to help us.

　　四、指時(shí)間

　　36. ---What time is it by your watch? --- Its ten minutes past two.

　　37. ---What day is it today? ---Its Friday.

　　38. ---Whats the date today? ---Its May 1st.

　　39. Its early spring, but its still very cold.

　　make it + 時(shí)間 把時(shí)間定在；約定

　　40. Lets make it eight oclock.

　　41. Let's make it three o'clock sharp.我們約定3點(diǎn)整吧。

　　Its time (for sb.) to do sth.

　　42. Its time to have supper. = Its time for supper.

　　53. Its time to take a walk.

　　44. It is time for us to set out.

　　45. It is time for you to go to bed.

　　Its time for sth.

　　46. Its time for class. (口語中可省略為Time for class.)

　　47. Its time for lunch. (口語中可省略為Time for lunch.)

　　48. Its time for a break. (口語中可省略為Time for break.)

　　49. Its time for a rest. (口語中可省略為Time for rest.)

　　50. Its time for dinner. (口語中可省略為Time for dinner.)

　　Its high/about time + did/should (虛擬語氣)

　　51. Its high time you left.

　　52. Its about time we should work hard at our lessons.

　　It is/has been + 時(shí)間 + since

　　53. Its twenty years since she left me.

　　54. It has been 20 years since I left here.

　　55. I heard it had been 20 years since they departed from each other.

　　It was/will be + 時(shí)間名詞 + before 從句 在多長時(shí)間后才發(fā)生某事

　　56. It was twenty years before they met again.

　　57. It wont be long before you recover.

　　58. It will be two years before I come here again.

　　五、指天氣等自然現(xiàn)象

　　59. Its very cold in winter in Haerbin.

　　60. Its five degree below zero.

　　61. It will be windy tomorrow.

　　62. It will snow heavily tomorrow.

　　63. The volleyball match will be put off if it rains.

　　64. It was snowing heavily when he went out.

　　65. ---Whats the weather like in Beijing? ---Its cloudy.

　　六、指距離、速度、金錢、度量

　　66. Its just two stops to the park. 到公園只有兩站路。

　　67. Its about ten kilometers from my home to my school.

　　68. Its about ten minutes walk from here to the zoo.

　　69. It is 90 dollars in price.

　　70. Its 200 mph in velocity. 速度是每小時(shí)200英里。

　　It is + 數(shù)詞 + meters/miles/kilometers long/wide.

　　71. Its three kilometers long for from east to the west.

　　72. Its 200 meters wide from this side to that side.

　　七、指環(huán)境情況

　　73. Its very quiet in the forest.

　　74. Itll be very interesting at the party today.

　　75. It is always very clean and tidy in my sons room.

　　76. Its very chilly in my room.

　　77. It was noisy when he got to the classroom.

　　78. If it is convenient to you, I am going to visit you.

　　79. It was exciting when we watched the astronauts taking space walks.

　　八、替代this或that

　　80. ---Whats this/that? ---Its my pencil sharpener.

　　81. Thats not interesting, is it?

　　82. This is your point, isnt it?

　　九、作形式主語

　　(一)、替代動(dòng)詞不定式

　　It is + adj. to do sth.

　　83. It is good to eat vegetables.

　　84. It is an honor to have been asked to speak at the meeting.

　　It is + adj. +for sb. to do sth.

　　注意：此結(jié)構(gòu)中的形容詞是描述事情的、說明句尾動(dòng)詞不定式特征的形容詞。這些形容詞主要有certain, clear, dangerous, difficult, easy, hard, illegal, impossible, important, obvious, possible, polite, proper, right, unnecessary, unimportant, unlikely, useless, useful等。

　　85. She is such an eccentric woman that it is difficult for anyone to get on well with her.

　　86. It is a good custom for young people to give up their sets to old people in the buses trains, or subways.

　　It is + adj. + of + sb. to do sth.

　　注意：本句型中的形容詞一般表示人(邏輯主語)的某種特性，要么是夸贊，要么是貶損。主要有brave, careful, careless, considerable, cruel, clever, foolish, good, grateful, generous, impolite, kind, nice, polite, rude, silly, stupid, thoughtful, unkind, wise, wrong,等。

　　87. It is kind of you to lend me so many books.

　　88. It is clever of you to solve so difficult a problem.

　　89. It is wise of you to refuse his offer.

　　90. It is remarkable of her to be always working like this.

　　It is a pity(for sb.) to do sth. 很遺憾做某事

　　91. It would be a pity to miss the opening ceremony.

　　92. It is a pity for you not to go to Paris with us.

　　It is a great relief (to sb.) to do sth. 做是一大慰藉；真叫人送了一口氣

　　93. It is a great relief to have rain after a long time of drought.

　　94. Its a great relief to me to know you are safe.

　　95. Its a great relief to hear that she won the prize.

　　It is worth while to do sth. 做是值得的

　　注意：本句型就相當(dāng)于It pays to do sth.；worth while 不要寫成worthwhile。

　　96. It is worth while to take a trip abroad.

　　97. It is worth while to learn English.

　　Its best to do sth. 最好做某事 = To do sth. is best.

　　98. Its best to set off tomorrow. 最好明天動(dòng)身。 = To set off tomorrow is best.

　　99. Its best to review the lessons one more time. = To review the lessons once more is best.

　　Its better to do A than to do B = To do A is better than to do B.

　　100. It is better to borrow than to buy. = To borrow is better than to buy.

　　101. Its better to stay at home than to go to the cinema. = To stay at home is better than to go to the cinema.

　　How is it possible to do sth.? 這怎么可能？

　　102. How was it possible to fall down from the third floor without being hurt?

　　103. How is it possible for a girl of ten to fly an airplane?

　　Its no use to do sth. 做是沒有用的

　　104. Its no use to argue with him.

　　105. He doesnt know the answer, so it is no use to ask him.

　　It takes (sb.) + 時(shí)間/條件 + to do sth. 某人花了多少時(shí)間做某事；做某事需要(條件)

　　106. It takes me half an hour to walk from here to school.

　　107. How long does it take to fly Being to London?

　　108. It takes patience and hard work to master English.

　　It costs sb. some money to do sth. 某人花多少金錢做某事

　　109. It cost him a great deal of money to take the trip.

　　100. It cost me 2000 dollars to collect these stamps.

　　It occurs to sb. to do sth. 某人突然想到做某事

　　111. It never occurred to me to take advantage of you. 我決沒有想到過要占你便宜。(利用你)

　　It feels + adj. + to do sth.

　　112. It feels pleasant to talk with her. 同他談話使人感到愉快。

　　113. It must feel strange to have a twin brother.

　　114. It feels unhappy to be with him.同他在一塊讓人感到不舒服。

　　115. It feels nice to take a walk in the evening. 晚間散散步感覺很好。

　　其它例句

　　116. It seems a pity not to have taken his advice.

　　117. It wont hurt to postpone the party for a few weeks.

　　118. It did surprise me to hear you say so.

　　119. It gave great pleasure to have finished this work ahead of the dead line.

　　(二)替代動(dòng)名詞

　　動(dòng)名詞可以直接位于句首作主語，但為了強(qiáng)調(diào)，或動(dòng)名詞過長時(shí)，要用it作形式主語置于句首，而把動(dòng)名詞放到句子最后。這也是英語尾部重壓原則所要求的。

　　It is no good/use (in) doing sth. 做是沒用的；做是白費(fèi)力氣的

　　= It is of no good/use doing sth.

　　= It is not any good/use doing sth.

　　120. It is no sue crying over spilt milk.覆水難收，悔恨無益。

　　121. It is no use trying to drown your sorrows in drink. 解酒澆愁無濟(jì)于事。

　　122. Its no good getting cross with him.和他生氣沒有用。

　　123. Its no good reading without full understanding.

　　Its exciting doing sth.

　　124. Its exciting meeting you here.

　　Its dangerous doing sth.

　　125. Its dangerous playing with fire.

　　Its foolish doing sth.

　　126. Its foolish behaving like that.

　　Its pleasant doing sth.

　　127. Its pleasant lying in the sun.

　　Its fun doing sth.

　　128. Its fun being a magician.

　　Its no use doing sth. 做沒有用

　　129. Its no use crying over spilt milk.

　　130. Its no use regretting.

　　131. Its no use you running away.

　　注意：

　　1. 辨析：Its no use doing sth. Its no use to do sth.

　　132. Its no use doing sth. 通常指比較一般的情況。

　　133. Its no use to do sth.常指具體的情況，也就是指在某一特定的場(chǎng)合所發(fā)生的事情。

　　2. 類似句型

　　134. Its useless to do sth.

　　135. Its of no use to do sth.

　　Its a nuisance doing sth. 做很煩人。

　　136. Its a nuisance having to do so much homework.

　　注意：這一結(jié)構(gòu)中的動(dòng)名詞還可加ones即物主代詞來充當(dāng)該動(dòng)名詞的邏輯主語。

　　137. Its a waste of time your talking to him. It is just like casting pearls before swine.

　　138. It was great encouragement to us their coming to help.

　　139. It is useless doing that over and over again.

　　注意：辨析：Its nice to do sth. Its nice doing sth.

　　140. Its nice to do sth. 常用于見面或活動(dòng)開始； Its nice doing sth.則用于分手或活動(dòng)結(jié)束。

　　141. Its nice taking a walk in the evening.

　　142. Its so nice sitting near a fire in winter.

　　143. Its nice to meet you here.

　　144. Its nice to have a talk with you. (說話開始)

　　145. Its nice talking with you. （談話之后）

　　Its hard doing sth.做某事有困難

　　146. Its hard learning English well.

　　Its interesting doing sth.做某事有趣

　　147. Its interesting going sight seeing.

　　Its easy doing sth.做某事容易

　　148. Its easy working out this problem.

　　(三)、替代主語從句

　　句型一：It + be + adj. + that從句

　　149. It is clear that she is a spy.

　　140. Is it true that you won the contest?

　　151. It is true that he didnt tell the truth.

　　152. It is quite plain that Tom didnt want to go there with us.

　　153. It is obvious that the driver couldnt control his car .

　　句型二：It is + adj. + that (虛擬語氣)

　　154. It is strange that such a rich man should be so stingy.

　　155. It is natural that such a hardworking student should pass the exam.這么用功的學(xué)生通過考試時(shí)很自然的事。

　　156. It is important that he should not do it. 他不該做那事是有必要的。

　　157. It isnt surprise that Marry should marry him. 瑪麗要同他結(jié)婚并不奇怪。

　　157. It is necessary that you should go to the doctor.

　　158. It is strange that we should meet here. 我們竟然在此相遇，真奇怪。

　　159. It is a pity that we should refuse to attend the meeting.

　　句型三：It + be + 名詞或名詞詞組 + that從句

　　It is a pity that 真是遺憾

　　160. It is a pity that we have to leave tomorrow.