it 作形式主语的固定句型

题目

it 作形式主语的固定句型

答案

动词不定式,动名词或主语从句作主语时,通常把它们放在谓语动词前,而用it作形式主语,放到句首,常见句型有：
1.It + be + 形容词+主语从句,如：
It is uncertain whether he can come to Jenny’s birthday party or not.
2.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.
3.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.
It is not decided who will give the operation to the patient.
4.It + 不及物动词(seem,appear,happen等) + 主语从句,这类不及物动词有：appear,happen,seem等,如：
It seemed that he didn’t tell the truth.
It happened that I was out when he called.
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,如：
It’s necessary for the young to master two foreign language.
It is unwise to give the children whatever they want.
这类形容词有：easy,difficult,hard,important,possible,wise
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：
It’s very kind of you to help me with the work.=You are kind to help me.
It seemed selfish of him not to share his dictionary with others.=He seemed selfish not to share his dictionary with others.
7.It + be +名词词组 + 动词不定式,如：
It is not a good habit to stay up too late.
8.It + be + 名词或形容词 + 动名词,这类名词和形容词常常是：good,no good,no use,a waste of,useless,senseless等,
如：
It’s a waste of time talking to her any more.
It is no use arguing about the matter with him.
9.It + take ( sb.)+ 时间（金钱）+ 动词不定式,如：
It took the workers almost three years to finish building the dam.
It will take a whole day to get to the top of the mountain on foot.