IT用法小结_it用法小结
IT用法小结由刀豆文库小编整理，希望给你工作、学习、生活带来方便，猜你可能喜欢“it用法小结”。
It用法小结
王婷婷
It的用法复杂多变，现对it的用法小结一下。
1.It 用作人称代词：It可用代词，作人称代词，指前面已经提到过的事物，动物或人，在句中作主语或宾语．
例如：1）.He bought a dictionary and gave it to me.(指代物品the dictionary)2）.Don’t think any more about it.(指代事件）3）.---Who is that ?---It’s me.Open the door, please.(指代人）
2.It 用作非人称代词：It 也用作非人称代词，常常用作句子主语，表示天气，日期，时间，温度，距离等．
1）.It was raining when I left the office.(表示天气)2）.It is February 14th today.(表示日期)3）.It is an hour’s walk from my home to the school.(表示距离)IT在表示时间时要注意以下的一些句式：
① It be … since...该句型主句中的 it 指时间,主句中是时间作表语，其时态是现在时或完成时，since 引导的从句通常是一般过去时态。如果主句是一般过去时，从句则用过去完成时。
It is(has been)5 years since his father died.It was 5 years since I had enjoyed myself so much.It is(has been)5 years since I smoked.②It be...when...该句型中的 when 引导的是一个时间状语从句，主句中的 it 指时间，表语由具体的时间充当。常译为“当……的时候，是……”。
It was 5 o'clock when he came here.③It be...before...该句型主句中的 it 指时间, 主句中的时态常是将来一般时或过去时两种时态．主句中的表语多是long, not long , 3 days , 2 weeks 等表示时间段的词或短语。常译为“……之后……”“过多久....才...”。
It was 3 days before he went to Beijing.It will be not long before he finishes his job.④It is time(about time , high time)that...该句型中that 后的从句应该用虚拟语气，① 常用过去时态表示虚拟．② 有时也用should + 动词原形，should 不能省。常译为“是（正是）……的时侯……”。
It is time that children should go to bed.= It is time that children went to bed.⑤It is the first(second …)time that …该句型要和上一个句型区别开来。该句型中的 that 从句不用虚拟语气，而用完成时态。至于用什么完成时态，由主句的谓语动词的时态决定。如果是一般现在时，后面从句用现在完成时态；如果是一般过去时，后面从句则用过去完成时态。该结构中 that 可以省去；it 有时用 this 替换，常译为“是第一
（二）……次……”。
It is the first time I have been here.= This is the first time I have been here.3.It作形式主语
替代作主语的从句、动词不定式、动名词，为避免“头重脚轻”，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）.替代作主语的动词不定式，其句型为
①
It be adj.(for∕of sb.)to do sth.常见的形容词有：
important, neceary, natural ,easy, safe, common, normal, hard, difficult, dangerous, unusual, impoible, pleasant,foolish,clever,brave,kind,wise 等。
②
It takes sb.sometime to do sth.2）
替代作主语的动名词的常见句型：
It’s no good/ no use / usele doing… 3).替代作主语的从句常见句型
①It is + noun(a pity, a shame, no wonder)+从句
②.It is adj.+clause ③It is v-ed that…=sb/sth is to do
(verb=say, report, think, believe, hope, expect, agree, accept, decide, determine, intend, plan, understand, know,suggest,demand,request,order等）如果为表示命令，建议，要求的词，则从句要用虚拟语气，及shoule+v.（should可省）
④It verb(to sb.)that…= sb/sth verb to do(verb = appear, seem, happen, occur, turn out 等)
⑤It verb sb.+ clause= It is v-ing + clause
It+surprise/delight/interest/disappoint/worry/disturb/annoy/amaze/bother/concern/frighten/please/anger sb.that…
4.It作形式宾语
当不定式、动名词、that 从句作宾语，又有自己的宾语补语时，要用it 作形式宾语，而把真正的宾语后置。能够用于形式宾语句型的动词有think, make, find, consider, feel, take，suppose,keep等。如：
Marx found it important to study the situation in Ruia.The fisherman made it a rule that he never cast his net more than four times a day.We think it neceary reading aloud every morning to improve our English.以下的动词在接宾语从句时需要先加it再接从句：hate,like,dislike,love,appreciate,enjoy,prefer等。
eg.I would appreciate it if you would like to teach me how to use the computer.I hate it when people talk with their mouths full.I like it in the autumn when the weather is clear and bright.5.It 用在强调句型中
①It is + 被强调部分 + that...该句型是强调句型。将被强调的部分放在前面，其它部分置于that 之后。被强调部分可以是主语，宾语，或状语。强调的对象是人时,可用who, whom, that,其余情况一律用 that;当强调对象在从句中做主语时用who, that,当强调对象在从句中作宾语时用whom ,that如果把这种句型结构划掉后，应该是一个完整无缺的句子。这也是判断强调句型与其它从句的方法。
It was about 600 years ago that the first clock with a face and an hour hand was made.It was they that(who)cleaned the claroom yesterday.It was in the street that I met her father.②.强调对象是疑问词
Why is it that you want to leave so soon? ③.It is not until + 被强调部分 + that...该句型也是强调句型。主要用于强凋时间状语，译成汉语 “直到……才……”，可以说是 not...until...的强调形式。
It was not until she took off her dark glaes that I realized she was a famous film star.= Not until she took off her dark glaes did I realize she was a famous film star.= I didn't realize she was a famous film star until she took off her dark glaes.
