文档介绍：PETS第四级重点语法资料
It做形式主语
It可以用作先行词,作为句子形式上的主语,而把真正的主语移到句子后部去。这种it成为先行主语(Preparatory Subject)。这样可以使句子变得更平稳,避免主语太长,显得头重脚轻。可移到句子后部去的主语最常见的是不定式。句子谓语主要有下面几种类型:
a、be+形容词+不定式:
It is easy to criticize 。
(比较:To criticize others is easy)
It’s nice not to be dependent on 。
be+名词+不定式:
It was his duty to take care of the 。
It’s a privilege to visit your 。
be+介词短语+不定式:
It was against my principle to do 。
It’s beyond me to say 。
及物动词+宾语+不定式:
It cost 100 dollars to repair the 。
It takes two to make a 。
It makes me sick to think about 。
不定式前有时可有for引导的短语,表示其逻辑上的主语:
What time would it be most convenient for me to call again?什么时候我再来方便?
It’s getting harder every day for a poor man to get a 。
用it作先行主语,代表动名词的情况也不少,这类句子用“be+名词”作谓语时最多,也可以“be+形容词”或其他结构作谓语。
a、It’s no use studying for an exam at the last 。
It’s no good standing here in the cold. Let’s go ,咱们回去吧。
b、It is worthwhile quarrelling with him?和他吵值得吗?
It’s hopeless trying to convince 。
c、It doesn’t matter waiting a few 。
It doesn’t make any difference my being 。
3)用it可以引导强调句:
It was Peter who lent us the 。
It’s today that he’s 。(不是明天)
4)如果将it+be置于find/think(that)之后,通常be和that可省略:
He thought (that) it (would be) better to say 。
2、形容词比较级的特殊用法
形容词比较急有些特殊用法,例如:
1)more…than有时可以把两种品质加以比较,表示“更多…而不是”:
This is more a war movie than a 。
2)more and more 这里结构可表示“越来越”:
The story gets more and more 。
3)the more…the more可表示“越是…越…”
The warmer the weather, be better I 。
4)more than常用在数词前,表示“超过…”“…多”:
He can’t be more than 。
More than 800 people attended the 。
5)less than常表示“不到…”或(美)“不太”:
In less than a week, the MS was 。
I bought it for