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 欄目類別:知識(shí)點(diǎn) >> 高中 >> 英語

it的用法

更新時(shí)間:2016/7/20 13:58:00  手機(jī)版

  it的概念:

  it可用作人稱代詞、指示代詞、先行詞及引導(dǎo)詞等。

  it 的用法:

  1、it可指天氣、溫度、時(shí)間、距離等 。

  如:It is cold today, isn't it?

  2、用作人稱代詞,代替前文提到過的事物。

  如:The dog is not  acold-blooded animals.  It doesn't need to hibernate.

  3、為避免重復(fù),it可用來代替前面說過的短語或句子。

  如:I tried to persuade my father to give up smoking, but found it impossible. (it=to persuade my father to give up smoking)

  4、代替指示代詞this,that。

  如:—What's this?

  —It's an album.

  —Whose new bike is that?

  —It's Mary's.

  注:it與one,that的區(qū)別:

  it=the(this, that)+名詞,特指并且代替前面所提到的某特定事物。

  如:He's bought a new car, so he drives it everywhere to show ito ff.

  one=a+名詞,one指前面提到的同類事物中的不同的另一個(gè)。

  如:He needs a computer, but he can't afford one.

  that=the+名詞,that指代的名詞與前面的名詞屬于同一類,但不屬同一個(gè)。

  如:The population of China is larger than that of Japan.  that指代population,但其后有一個(gè)of短語作定語,以區(qū)別于the population of China。

  注:it與that的異同:

  it指同一事物,that指同類但并不是同一事物。

  如:I like the climate of Kunming more than that of Beijing.

  The climate of Kunming is mild, and I like it.

  5、It/This/That+be+the first(second, third...) time+that-clause 這個(gè)句型表示截止到說話時(shí)為止的某人的一種經(jīng)歷,關(guān)鍵是注意time前有序數(shù)詞,主句是一般現(xiàn)在時(shí)is時(shí),從句要用現(xiàn)在完成時(shí);如果主句用一般過去時(shí)was時(shí),則從句須相應(yīng)地用過去完成時(shí)。

  如:This is the first time(that) these Europeans have visited the Great Wall.

  It was the fifth time(that) I had paid a friendly visit to America.

  6、在一些相對(duì)固定的詞組中,沒有特殊含義,經(jīng)常不翻譯。

  如:He's never really made it as an actor. 作為演員,他從未獲得過真正的成功。

  It is my turn. 輪到我了。

  強(qiáng)調(diào)句中的it:

  可以用來改變句子結(jié)構(gòu),使句子的某一成分得到強(qiáng)調(diào):

  1)強(qiáng)調(diào)句的基本句型it's/was+被強(qiáng)調(diào)成分+that/who+其他成分

  原句:I told Jim the news in our office yesterday.

  強(qiáng)調(diào)主語:It was I that/who told Jim the news in our office yesterday.

  強(qiáng)調(diào)賓語:It was Jim that I told the news in our office yesterday.

  或:It was the news that I told Jim in our office yesterday.

  強(qiáng)調(diào)地點(diǎn)狀語:It was in our office that I told Jim the news yesterday.

  強(qiáng)調(diào)時(shí)間狀語:It was yesterday that I told Jim the news in our office.

  2)強(qiáng)調(diào)句的一般疑問句型Is/Was+it+所強(qiáng)調(diào)部分+that/who...?

  如:Was it you that told Jim the news in your office yesterday?

  3)強(qiáng)調(diào)句的特殊疑問句型疑問詞+is/was+it+that/who...?

  如:Who was it that told Jim the news in your office yesterday?

  【注】強(qiáng)調(diào)句與主語從句雖然在形式上很相似,即都含有it is(was)...that。但,區(qū)別在于:強(qiáng)調(diào)句去掉it is(was)…that之后,句子結(jié)構(gòu)仍然完整,而主語從句卻不能這樣。

  如:(It is)our hope(that) the two sides will work towards peace.

  解析:去掉It is…that之后,句子是不成立的。由此得出該句不是強(qiáng)調(diào)句,而是一個(gè)簡單的主語從句,it是形式主語,從句是真正的主語。

  “it”的用法:

  1、it 作形式主語:

  it 在句中可作形式主語,而真正作主語的主語從句需要放在句子的末尾。主語從句后置常用以下幾種結(jié)構(gòu):

  1)It is/was+adj.+subject-clause可用于此句型的形容詞有:

  clear, certain, funny, good, impossible, likely, natural, obvious, possible, probable, strange, surprising, true, unusual, wonderful等。

  如:It is obvious that going for sports will do a lot of good to your health.

  2)It+be+adj./n.(forsb./ofsb.)+todosth. 該句型中的形容詞通常表示事物的特點(diǎn)或特征的,如:

  difficult, hard, easy, impossible, necessary, important等,此時(shí)用for;或表示人的性格特征或特點(diǎn)的,如:

  nice, good, bad, kind, silly, foolish, wise, clever, careless, rude, brave, cruel, careful, grateful等,這時(shí)要用of 。

  3)It is/was+名詞詞組+subject-clause可用于該結(jié)構(gòu)的名詞詞組有:

  a pity/duty, a good thing, no surprise, good news, an honor, a fact, a mystery, a shame, manners等。

  如:It's a pity that I didn't attend the party.

  4)It is/was+V-ed+subject-clause可用于該結(jié)構(gòu)的動(dòng)詞的過去分詞有:

  said, reported, thought, supposed, believed, hoped, expected, known, decided, announced, arranged等。

  如:It is said that something had been done to end the pollution.

  注:本句還可改寫為:Something is said to have been done to end the pollution.

  5)It+vi.+subject-clause可用于該結(jié)構(gòu)的動(dòng)詞有:appear, seem, happen, occur等。

  如:It appeared to scientists that the stars had moved.

  6)It doesn't matter(makes no difference,etc.) +連接代詞或連接副詞引起的從句作賓語。

  如:It doesn't matter whether he'll join the army or not.

  It makes no difference where we have the conference.

  7)一些固定句型:

  It takes sb. some time to do sth.

  如:It will take you two days to get there on foot.

  It costs sb. some money to do sth.

  如:It costs 1,000 dollars to fly to America.

  It is/was no use(useless) doing(做什么是沒有用處的)

  如:It's no use arguing with him.

  It is/was no good doing(做什么是沒有好處的)

  8)以下句型結(jié)構(gòu)中需要用虛擬語氣

 、 It is/was important(necessary, strange) that...;

  It is/was ordered(required, suggested, proposed) that...;

  It is/was a pity(a shame) that...表示遺憾等感情的句子中,主語從句要用“should+動(dòng)詞原形”,should可以省略。

  如:It's necessary that he(should) be operated on at once.

 、 It is (high)time that...結(jié)構(gòu)中用should+動(dòng)詞原形(should不能省略)或動(dòng)詞過去式。

  如:It is high time that you should make(made) full use of your time to go over your lessons.

  2、it作形式賓語:

  1)動(dòng)詞consider(feel, find, think等)+it+形容詞(名詞)+不定式(動(dòng)詞-ing形式,從句)。

  如:She thinks it no use telling me.

  2)主語+appreciate(enjoy,like,love,hate)+it+if(when)...結(jié)構(gòu)

  如:We would appreciate it if you could come to help us.

  3)dependon, relyon, see to(負(fù)責(zé)/設(shè)法做到), takeforgranted(習(xí)以為常)等短語后跟that從句時(shí),要以it作形式賓語。

  如:We're depending on it that he will finish the job by Friday.

  “it ”引起的幾個(gè)易混淆的時(shí)間句型:

  1)It be+時(shí)間+since-clause 這個(gè)句型表示從since從句謂語動(dòng)作發(fā)生以后到現(xiàn)在或過去所經(jīng)過的一段時(shí)間,意為“自從…以來已多久了”,主句多用一般現(xiàn)在時(shí),從句用一般過去時(shí),如果表示過去的情況,主句一般用過去時(shí),從句用過去完成時(shí),或主句用過去完成時(shí),從句用一般過去時(shí)。

  注:since引導(dǎo)時(shí)間狀語從句時(shí),從句若使用終止性動(dòng)詞,則表示該時(shí)間是主句時(shí)間段的終點(diǎn)(時(shí)間從現(xiàn)在算起);若從句使用延續(xù)性動(dòng)詞,則表示該動(dòng)作狀態(tài)的結(jié)束(時(shí)間從過去算起)。

  如:It's five years since they got married. 他們結(jié)婚已經(jīng)5年了。

  It's five years since they were married. 他們離婚已經(jīng)5年了。

  It's ten years since his father was a worker. 他父親不當(dāng)工人已經(jīng)10年了。

  I haven't seen him since we were boys together. 我們長大以后再?zèng)]有見過面。

  2)It be+時(shí)間+before-clause 這個(gè)句型中的時(shí)間一般為表示一段時(shí)間的詞語(如:long years, months, weeks, days, hours, minutes),主句中的謂語動(dòng)詞用肯定式,意為“過多長時(shí)間才…”。主句的謂語動(dòng)詞是否定式時(shí),意為“沒過多長時(shí)間就…”。主句的時(shí)態(tài)可用過去時(shí)was或?qū)頃r(shí)willbe;用was時(shí),before從句的動(dòng)詞用一般過去時(shí);用willbe時(shí),before從句常用一般現(xiàn)在時(shí)。 如:It was not long before she learned those poems by heart. 她沒過多久就背會(huì)了那些詩。

  It was long before the police arrived. 過了很久警察才來。

  It will be hours before he makes a decision. 要過好幾個(gè)小時(shí)他才會(huì)作出決定。

  It will not be hours before we meet again. 要不了幾個(gè)小時(shí)我們還會(huì)再見面的

  3)It be+時(shí)間+when-clause 這個(gè)句型中,it指時(shí)間,而且表示時(shí)間的詞語前沒有介詞(時(shí)間一般是具體時(shí)間)。主句和從句中的謂語動(dòng)詞在時(shí)態(tài)上是一致的,主句是willbe,when從句用一般現(xiàn)在時(shí)代替將來時(shí)。

  如:It was already 8 o'clock when we got home.

  It will be late afternoon when they get there.

  4)It be+時(shí)間+that-clause 這個(gè)句型是個(gè)強(qiáng)調(diào)句型。

  如:It was at 5o'clock that he practiced playing the violin in the morning. (原句是:He practiced playing the violin at 5o'clock in the morning.)

  比較:It was 5o'clock when he started in the morning.(5o'clock前沒有介詞,這個(gè)是定語從句)

  5)It be+time+that-clause 這個(gè)句型屬虛擬語氣結(jié)構(gòu),不管主句中用的是is或was,that從句都須用動(dòng)詞的過去式或should+動(dòng)詞原形(但不及物動(dòng)詞通常用過去式),在time之前有時(shí)可以加上high 或about 以加強(qiáng)語氣。

  如:It is high time(that) he wrote a letter to his girl friend.

  It is time(that) we made people's life a little easier.= It is time that we should make people's life a little easier.

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