英语中为什么要用形式主语it呢 不用也不

Question

如题所述

Answer 1

为满足语法上的需要，避免句子头重脚轻
It is a hard job for the police to keep order in an important football match.
如果不用it做形式主语，那么句子就是：
(To keep order in an important football match) is a hard job. 括号内就是主语追答

主语复制掉了一点：
(For the police, to keep order in an important football match) is a hard job. 括号内就是主语