“It”作形式主语的句型
“it”作形式主语时无具体意义，真正的主语常由动名词，动词不定式和主语从句等担任，并被
后置。此用法常为避免句子句式不平衡或“头重脚轻”。
1.It is/was + 被强调部分+ that/who…
该句型是强调句型。被强调部分可以是主语，宾语，表语或状语。强调的主语如果是人，that
可以由 who 换用。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。
2. It is not until+被强调部分+ that..
该句型也是强调句型。主要用于强调时间状语，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 glasses that I realized she was a famous film star.
=Not until she took off her dark glasses 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 glasses.
3. It is clear /obvious/true/possible/certain. that…
该句型中it 是形式主语，真正的主语是 that 引导的主语从句，常译为“清楚(显然，真的，
肯定……)”是主语从句最常见的一种结构。
It is very clear that he's round and tall like a tree.
= That he's round and tall like a tree is very clear.4. It is important /necessary/right/strange/natural..that+(should) do
该句型和上一个同属一个句型。由于主句中的形容词不同，that 后的从句中要用虚拟语气
(should +动词原形), should 可以省去。
1) It is important that we(should) study English.
2)It is necessary that all the inventions(should)be used for good, not for evil.
5. It is said (reported, learned,believed, thought, announced,estimated.) that…
it 是形式主语，真正主语是 that 引导的主语从句。该结构常译为“据说(据报道，据悉……)”。
1)It is said that he will be late today.
6.It is suggested(ordered, required, arranged, proposed, decided, recommended...)
that…+(should) do
主句中的过去分词充当形容词，是表示请求，建议，命令等词时，that 后的从句要用虚拟语
气(should+动词原形),should 可以省。常译为“据建议；有命令……)”。
1) It was decided that the meeting(should) be put off till next Saturday.
2) It was arranged that they(should) leave the following week.
7. It is a pity(a shame...)that…
该句型中，that 后的从句一般用虚拟语气(should+动词原形),should 可省去.表示出乎
意料，常译为“竟然”。没有这种意义时，则不用虚拟语气。It is a pity that such a thing(should) happen in your class.
这种事竟然发生在你们班上，真是遗憾!
It is a pity that he is ill.
他生病了，真遗憾!
8. It is time(about time,high time)that …
该句型中 that 后的从句应该用虚拟语气，值得注意的是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……”。
1)It's high time that you went to see your sick friend.
2)It's high time that we should put all our heart to study.
9.It 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 l have been here.= This is the first time I have been here.
10. It is.since …
该句型主要用作处理瞬间动词的完成时，又要和表示一段时间的时间状语连用的问题。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，而且是瞬
间动词。如果主句是一般过去时，从句则用过去完成时。11. It was... 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……”。
12. It 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……”。
13. It happens(seems, looks,appears, turns out, occurs to sb..)that...
it 是形式主语，that 引导的是主语从句，主句中的happen, seem等词是不及物动词.
It happened(so happened)that he met his teacher in the street. 碰巧……
It seems that he will be back in a few days. 看来……
14. It takes sb.... to do sth.
句型中的不定式是真正的主语，it是形式主语，句型中的直接宾语是时间。常译为“做……要
花费某人……”。
1) It took thousands of people many years to build the Great Wall.
2) It will take him three hours to go to Hangzhou by train.15. It is no good (use)/a waste of time doing sth.
句型中的真正主语是动名词短语，主句中的表语可以是no good,(not any good),no use,
(not any use)。
1) It is a waste of time sitting in front of the TV allday.
2)It's no harm drinking running water in that area.
16. It matters/doesn't matter whether(if)….
句型中whether(if)引导的从句是真正主语，该句型常译为“不论(是否)……没关系……
1) It doesn't matter what you say.
17.It is kind(of sb.)to do sth.
该句型中的不定式短语是真正主语，如果不定式的逻辑主语是由 of 引起，主句中的形容词必
须是能表示逻辑主语特征的形容词。常见的有：bad, brave, careless, clever, cruel, foolish,
good(好心的), honest, horrible,kind,lazy,modest, naughty, nice(有教养的),polite,rude,
silly, stupid, wise, wrong(错误的)等。这个句型可以改写为：sb. is kind to do sth.
It is kind of you to say so. =You are kind to say so.18. It is necessary(for sb.)to do sth.
该句型与上一个同属一个句型。如果不定式的逻辑主语是由 for 引起，主句中的形容词通常是
表示重要性，紧迫性，频繁程度，难易，安全等情况的形容词。常见的形容词有：
①important,necessary, natural
② easy, safe, common, normal, hard, difficult, dangerous, unusual, rare, impossible,
pleasant 等。
在①中的形容词作表语可以用从句改写，如：
It is important for her to come to the party.
= It is important that she(should) come to the party
19. It looks(seems)as if….
该句型中 it 无意义。as if 引导一个状语从句。常译为，“看起来好象……”如果与事实
不相符合，则用虚拟语气.
1)It looks as if he were hiding something.
20. It is no wonder/honor that.
1)He missed the first bus, so it is no wonder that he was late for the meeting.
