it 用法很实用的学案

It的用法
一、it用作代词的用法
1．it 用来指代时间、地点、距离、天气、气候、季节、温度、环境等或虚指的情境。

例如：It was nearly midnight when she came back.
2．代替有生命但不能或不必分阴阳性的东西(包括婴儿)。

如：What a beautiful baby---- is it a boy?
二、it可在句子中作主语或宾语，用来代替一个名词，一个短语，一个分句或一个句子，以避免它们在句子中的重复。

为了避免句中作真正主语的动词不定式短语、动名词短语和名词性从句(一般都比较长)置于句首时造成头重脚轻，习惯上用it作形式主语置于句首，指代后面的真正主语，使句子显得流畅,保持句子的平衡。

而且，作形式主语的代词只能用it ，不能用that，this等词.
㈠it作形式主语的用法
1.It + be＋形容词＋for sb./ sth.＋动词不定式
用于此句型的形容词有：easy，hard，difficult，possible，important，impossible，necessary，good，bad，natural, safe, common, normal, dangerous, unusual, rare, pleasant 等。

2.It+ be＋形容词＋of sb．＋动词不定式
此句型中的形容词主要描述某人的品德、特征。

能用于该句型的形容词有：kind, nice, wise, clever, brave, silly, foolish, stupid, polite, impolite, rude, friendly, careless, cruel, honest ,lazy, modest, naughty, selfish, wrong, right , 等。

3.It+ be ＋形容词/名词＋doing sth．
此句型中的形容词和名词常见的有：no use, no good, useless等。

如：It is no use crying over spilt milk. 覆水难收。

it作形式主语, that从句作真正主语,常见的句型有:
⑴ It + be + 形容词(obvious, true, , surprising, wonderful, funn y, , likely, etc.) + that…
⑵ It + be + 形容词(important necessary, strange, natural...) that sb. (should) do sth.
⑶ It + be + 名词词组(no wonder, an honor, a fact, a pleasure, a surprise, a pity, etc.)+ that…
⑷ It+ be +过去分词( said ,reported, considered, thought, known, found, believed, etc.) + that…
⑸ It+ be +过去分词(suggested, ordered, demanded, requested ... ) that sb. (should) do sth.
⑹ It＋不及物动词(seems, happens, appears, occurs)＋that…或It looks ( seems )+ as
if ...
㈡it作形式宾语的用法
由作形式宾语，真正的宾语后置的固定句式有下面几个类型：
1．主语+谓语（make, consider ,find ,feel ,think ,believe）+it+形容词/名词+动词不定式/从句
2．主语+谓语(like / love / enjoy / hate /appreciate/dislike)+it+从句如: I hate it when you can’t discuss things openly.
I like it that everyone passed the exam.
I would appreciate it if you would like to teach me how to use the computer..
3．主语+谓语+介词+it+从句
如：I’ll see to it that（务必，确保）everything is ready in time.
Can I depend on it（相信）that this won’t take place again?
4．主语+谓语+it+介词短语+从句
I took it for granted that they were not coming.
三．it 可用于强调结构,构成句型：It's +被强调部分+that/ who+句子的其他部分。

如果被强调部分是人,既可用that又可用who,其余的全部用that。

这一句型也可用于一般疑问句、否定句或特殊疑问句。

其特点是:去掉It is(was)及that (who)后,在不添词、不减词的前提下能重新构成一个意义完整的句子。

【注意】1.注意强调句的疑问句式及其在名词性从句中的语序。

强调句的疑问句式为：特殊疑问词＋is/was +that+句子其他部分？
它在名词性从句中语序为陈述语序。

如：I just wonder what it is that makes him so excited .
容易与强调结构混淆的固定句型：
⑴It is the first time ( that ) sb. have / has done sth.
It was the first time ( that ) sb. had done sth.
⑵It is ( high / about ) time ( that ) sb. did / should do sth. 该句型中that引导虚拟定语从句，修饰先行词time，意思是：某人早该做某事了。

It is high time (that ) he went to school .
⑶It is / has been + 时间段+ since sb. did sth.
It was+ 时间段+ since sb. had done sth.
若since从句中的谓语动词是终止性动词，表示“自某人做某事以来已经多久了”；若从句中的谓语动词是延续性动词，则表示“自某人不做某事以来已经多久了”。

如：It is10 years since we left our hometown. 自我们离开家乡已经10年了。

It is10years since we lived in that village. 自我们不住在那个村庄已经10年了。

⑷It will be+ 时间段+ before 从句(一般现在时)
It was+一段时间+before从句(从句用一般过去时)
此句型若为肯定句，意指“过了多久才…”，若为否定句，则是指“没过多久就…”
如：It will be hours before he arrives here.
It won’t be long before he comes back.
⑸It is +时间名词+ when…
It was 8 o’clock when he came back.（定语从句）
⑹It is +时间状语+that…
It was 3 years ago that he joined the army.（强调结构）
⑺It is +地点名词+ where…
It is the place where I was born.（定语从句）
⑻It is +地点状语+ that…
It was in the place that I came to know him.（强调结构）
(9) It is/was not until...that...
It was not until she got home that Jennifer realized she had lost her keys
四．替代词it, that与one的区别
it表特指，替代前文中出现过的同一名词；替代前文中出现过的同类名词时，用that和one。

that表特指，相当于“the+名词”，可代替单数可数名词或不可数名词（只指物不指人），one用于泛指，相当于“a/an+名词”，只代替单数可数名词（可表示人也可表示物）。

五．it对关系代词as的干扰
⑴______is known to everybody, the moon travels round the earth once every month.
A. it
B. As
C. That
D. What
⑵_____ is reported in the newspapers , talks between the two countries are making
progress.
A.it
B. As
C. That D What
以上两题考察了as引导的定语从句,若选that,句子应分别为：
It is known to everybody that the moon travels round the earth once every month.
It is reported in the newspapers that talks between the two countries are making p rogress. 六．it对关系代词which的干扰
Carol said the work would be done by October, ______ personally I doubt very much.
A. it
B. that
C. when
D. which
此题中which引导非限制性定语从句,代指主句的整个内容。

若用it,则该句为: Carol said the work would be done by October, but personally I doubt it very much.
又如：Tom's mother kept telling him that he should work harder, but ___ didn't help.
A. he
B. which
C. she
D. it
七．it对there be句型的干扰
_____ no need for us to discuss the problem again since it has already been settled.
A. It has
B. There has
C. It is
D. There is
_____ is no possibility ______ Bob can win the first prize in the match.
A. There … that
B. It … that
C. There … whether
D. It … whether
常见的there be句型有：
There is no doubt that / of 毫无疑问
There is no need to do /for 没有必要
There is no possibility that/ of 没可能
There is no sense in …是无意义的
There was a time when 曾经有一段时间…
There is no chance that/ of 没有…的机会
八．其它含有it的常见句式和短语：
It takes sb. ... to do sth.
It remains to be seen有待于观察／证明
例如：Having a trip abroad is certainly good for the old couple, but it remains ___whether they will enjoy it.
A. to see
B. to be seen
C. seeing
D. seen
It turned out that…最终结果是，终于
It is up to sb. to do sth. 该由某人做某事
It goes without saying that…不言而喻
it也常用于某些习惯用语中，各该习惯用语有具体意义，但it并无具体意义。

如：
take it easy别着急，慢慢来make it 成功get it 懂了，明白了
it all depends视情况而定I can’t help it 我没有办法。