it+的基本用法及句型5页

1、语法专项复习之It的基本用法及句型It的基本用法：1. 人称代词it，是第三人称单数中性，代表前文已提到过 的一件事物。如： That vase is valuable. It is 200 years old. 2. 当说话者不清楚或无必要知道说话对象的性别时，也可用it来表示。如： Its a lovely baby. Is it a boy or a girl? 3. it可用来指代团体。如： The committee has met and it has rejected the proposal. 4. it用以代替指示代词this, that。如： - Whats this? -

2、 Its a pen. 5. 作指示代词的it，常用以指人或物。如： - Who is making such a noise? - It must be the children.6. it常作无具体意义的主语，表示天气、气候、温度、时间、地点、距离等意义。如： It is half past three now. It was very cold; it snowed and grew dark. 7. it也常用来表示一般的笼统的情况。如： Its awfulIve got so much work I dont know where to start. Take it easy. 8.

3、 it充当形式主语（主要见句型中）。如： It is difficult to translate this article. It is no use going there so early. 注意：在上述诸例中，后置的真正主语可以取代先行it的位置，而出现于句首。 To translate this article is difficult. Going there so early is no use.但：也并非所有it形式主语结构都可作上述转换。如： It seems that John is not coming after all. It happened that John w

4、as the only witness. 上述两例只能转换为： John doesnt seem to be coming after all. John happened to be the only witness.9. It作形式宾语（主要见句型中），主要谓语动词为find,consider,feel,make,think等。如： I found it difficult to explain to him what happened. He thought it no use going over the subject again. We must make it clear to

5、the public that something should be done to stop pollution.1. that替换单数可数名词或不可数名词；one只替换单数的可数名词。The vase on the left is more beautiful than the one /that on the right.The coffee produced in Brazil is more famous than that in Mexico.注意： it与one(ones), that(those)的区别：2. that只用于替换表示事物的名词; 而one替换表示人和表示事物的

6、名词皆可。His younger sister is taller than the elder one.I need that plastic bags, not the paper ones.3. that(those)用于替换有定冠词的名词；one(ones)用于替换有不定冠词的名词。The style of the building is similar to that/the one of a temple.A CD player made in Japan costs more than one made in Hong Kong.4. that(those)一般不带前置定语，但必

7、须有后置定语。one(ones)都可。当替换词的后置定语用所有格的of短语或当替换词被所有格修饰时，不用one(ones)而用that of(those of).The windows of your flat are cleaner than those of mine.A grandparents job is easier than that of a parent.5. It指特定的前面提到过的事物，即it和它替换的是同一个事物，it前无修饰语；而one用于替换与前提事物有共同之处但并不完全一样的事物，因此，one之前或之后一定有修饰语来加以区别。I bought a dictiona

8、ry three years ago and I am still using it now. I bought a dictionary three years ago but I am going to buy a new one soon.1. 强调句型 结构形式是：It be（它的各种变体）被强调部分that/who其它成分。判断方法：去掉It be-that/who结构，句子仍保持完整。如： It was Jane that/who called this morning. It was a parcel that she brought him.注意强调句型的几种变形形式：1、Is

9、/Wasitthat?2、Who/Whom/When等+is/wasitthat?3、It can be that .4、It was/ is not until that .等等。It的有关句型：注意强调句型与定语从句、主语从句的区别：强调句中的Itis/wasthat/who去掉后，将语序进行适当调整，可 以得到一个结构和意义都完整的句子，而定语从句不是这样；如果是主语从句，去掉Itis/wasthat/who后句子就无法成立。强调句型中的that/who只是句型的一个标志，而引导定语从句的that/who在从句中作主语或宾语。试比较：1）ItwasJackwho/thatImetinth

10、estreetyesterday.强调句型ImetJackinthestreetyesterday.2）ItisthebookthatIhavebeenlookingfor. 定语从句Ihavebeenlookingforthebook.成立，但含义不同3）ItisafactthatEnglishisacceptedasaninternationallanguage. 主语从句 AfactEnglishisbeingacceptedasaninternationallanguage.（不能成立）2. Itis/hasbeen一段时间since从句 意为:“自以来已有多长时间了” 。如： Ith

11、asbeenmanyyearssinceIwaslastinLondon3. Itis/was/willbe+一段时间+before从句 表示“在（做某事）前, 过了多长时间”，或“过了多长时间,才”。如： It willbemorethan100yearsbeforethecountrybegins onceagaintolookasitdidbefore. 4. It(this/that)iswaswillbe+the序数词 +time(month/week/year)+that从句 意为“这是那是这将是某人第几次做某事了”。如：注意：主句谓语动词用is时，从句用现在完成时；主句的谓语动词

12、用was时，从句用过去完成时；主句的谓语动词用willbe时，从句的谓语动词用一般现在时表示将来。如： It/ThisisthefirsttimeIhavebeenhere. 5. It+be+adj./n.(forsb./ofsb.)+todosth. 该句型中的形容词通常是表示事物的特点或特征的如difficult，hard，easy，impossible，necessary，important等，此时用for；或表示人的性格特征(感情色彩) 如nice，good，bad，kind，silly，foolish，wise，clever，careless，rude，brave，cruel，ca

13、reful，grateful等，这时要用of .如： Infact it isahardjobforthepolicetokeeporderinanimportant footballmatch.6. Itbe过去分词that从句 适用该句型的过去分词主要有said,reported,announced,hoped,thought, told，believed，expected，decided，suggested,known等。该句型常可以转换成含有宾语从句的复合句。如： Itissaidthattheyaregood. Theyaresaidtobeverygood.8. Itbe形容词th

14、at从句 可用于此句型的形容词还有wonderful，true，good，right，wrong，（un）important，useless，surprising，clear，unusual，lucky，certain等。后常用虚拟语气+（should)。如： Itisimportantthatwe(should)studyhard. It is natural that he (should)say so.7.It+be+awasteoftime/nogood/nouse+doingsth. Itisnousecryingoverspiltmilk.谚牛奶已泼，哭也无用。9. Itbe名词（

15、词组）that从句 适用该句型的名词（词组）还有apity，anhonor， agoodthing，afact，asurprise，goodnews等。如：Itisapity(that)youmissedthesportsmeetinglastweek. 10. Itseemappearhappen适当形式that从句该句型常可以转换成含不定式的简单句。如： Itseemsthatthereisabigwastepipecomingdownfromthetown.Thereseemstobeabigwastepipecomingdownfromthetown.11.Itdoesntmatter

16、/Itsnowonder/Itdoesntmaketoomuchdifference等 when/where/which/whether等从句如： Doesitmatterifhecantfinishthejobontime? (It is)nowonderthat theyshouldhelpeachotherwiththeirstudies, because they are classmates.12. Itis（high/about）timethatsbdid/shoulddosth 该句型意为“是该某人做某事的时候了”。这是一个虚拟语气句型，表示与现在事实相反的虚拟语气。可转化为：

17、It is time to do结构。如： Its about time(that)Iwentandpickedupmy littlegirlfromschool.Itshightimethat we should go to school.It is time for us to go to school.13. It takes sb. +time/money等 +to do如： It took Mary 20 minutes to choose a suitable dress for the party14. It is up to sb. to do sth.（做某事由某人决定）如：

18、 Its up to you to decide what to do next.1.Is _ necessary to tell his father everything? A it B that C what D he2.I dont think _ possible to master a foreign language without much memory work. A this B that C its D it3.Does _ matter if he cant finish the job on time. A this B that C its D ADD练习题4.Toms mother kept telling him that he should work harder,but _ didnt help. A he B which C she D it5.I hate _ when people talk with their mouths full. A it B that C these D th