it做形式主语或宾语的用法

完成句子
found it difficult （1） They ________________（发觉…… 难） to finish their work in two days.
think it our duty （认为……是我们的 （2） We ________________ 职责） to clean our classroom every day. for her （对她来说） to （3） It is important _______ come to the party.
… … find possible 1. S+ think + it + necessary +( for sb. ) to do sth. /clause. feel important … …
…
a rule 2. S+ V + it + one’s duty + ( for sb. ) to do sth. /clause an honour … 3. S + V + it + no good + doing sth. no use
1.It 用作形式宾语
当不定式（短语）、动名词（短语）或从句在句子中作宾语时，为 保持平衡，避免句式结构的混乱，常用it作形式宾语，而将真正的宾 语放在句尾。此时it只起引导作用，无意义。
S + v + it+
adj.
(for sb) to do sth.. +
n
从句
doing sth
形式宾语
Sentence patterns:
It is not decided who will give the operation to the patient.
It is said that he has come to Beijing.
注意：如果主句中的过去分词是表示请求，建议，命令
等词如：suggested/ ordered / demanded /insisted / commanded... 等时 that 后的从句要用虚拟语
It 作形式主语代替不定源自、动词-ing短语、或从句。It is amazing that at my age I am still fit . It is easy to become addicted to smoking .
it is no good crying over spilt milk. (覆水难收)
1. I like _______ in the autumn when the weather is clear and bright. (MET2004) A. this B. that C. it D. one 2. I hate __when people talk with their mouths full. (MET98) A. it B. that C. these D. them
（should + 动词原形），should 可以省； 常译为，“据建议；有命令．．．）
It is suggested that the meeting ( should ) be put off. It was ordered that we ( should ) arrive there in two hours.
3. It + be + 名词词组 + 主语从句 这类名词有：a fact, a pity, a shame, an honour，a question等，如：
It’s a pity that you missed the exciting football match. It remains a question whether he will come or not. 注意：如若表示出乎意料之意时,从句一般用虚拟语气常译为“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.
It is unwise to give the children whatever they want.

6. It + be + 形容词 + of sb. + 动词不定式
这类形容词常是表示心理品质,性格特征的形容词， 如：kind, nice stupid, clever, foolish, polite, impolite, silly, selfish, considerate等。某人和 这些形容词可以构成主系表结构。如：
1. It+ be +adj.+主语从句
这是主语从句最常见的一种结构。
It is uncertain whether he can come to Jenny’s birthday party or not.
注意：如若形容词为 important / necessary， good/wrong natural...表达一种要求，命令或者责备时，多使用虚
1.The fact that she was foreign made ____difficult for her to get a job in that country .(2010.辽宁） A. So B. much C. that D. it
2. The doctor thought ____would be good for to have a holiday .（2010.全国II) A. this B .that C . one D . It 3. I don’t think _______ possible to master a foreign language without much memory work.. (MET90) A. this B. that C. its D. it
2. It 用作形式主语
当不定式（短语）、动名词（短语）或从句在某个句子中作主语时， 为保持句子结构前后平衡，避免头重脚轻，因此常用it作形式主语 置于句首，而将真正的主语放在句尾。此时it只起先行引导作用， 本身无词义。
adj It be + n p.p +
(for/of sb) to do sth 主语从句 doing sth


5. It + be + 形容词 + （for sb.）+ 动词不定式
这类句型常用形容词easy, difficult, hard, important, possible，wise等作表语，有时候为了强调不定式动作 的执行者，常在不定式前加for sb，译为“对某人来说 做某事怎么样”如： It’s necessary for the young to master two foreign language.
I'd prefer it if I didn't have to finish the work. 要是我不必完成那项工作，那就太好了。

2>.某些含有介词的动词短语如see to, depend on, answer for, rely on, insist on, look to, stick to 等结构中往往不能直 接接宾语从句；必须先由it担任形式宾语,再 接从句.
The use of “it”(I)
It作形式宾语
代替不定式、动词-ing短语、或从句。
He found it difficult to stop smoking
I think it best that you should do more exercise.
She thought it no good worrying about him
I'll see to it that everything is ready in time. 我将负责按时做好一切准备。
You may depend on it that Tom will help you with your English.(你放心，汤姆会帮助你学英语的。)
I’m counting on it that you will come. 我指望着你会来。
2. It + be + 过去分词 + 主语从句， 这类过去分词有：announced, believed, expected, hoped, decided, reported, said, shown等， 如：
It is reported that 16 people were killed in the earthquake.
4.It 作形式宾语的特殊用法

1>. 某些表示“喜、怒、哀、乐”的动词， 如like, enjoy, love, hate, dislike, appreciate等 后往往不能直接接宾语从句； 必须先由it担任形式宾语,再接从句.
We would much appreciate it if you could do us that favour. 要是你们能帮我们这个忙，我们将非常感激。
拟语气（should +V).但是如果只是表示陈述一个事 实而不是强烈的感情，完全可以用一般的陈述语气。 不过考试建议你还是多用虚拟语气
It is important that we (should) learn English well. It is necessary that he (should) remember these words.
It is no use arguing about the matter with him.

9. It + take ( sb. )+ 时间（金钱）+ 动词不定式，