Introductory it as Subject
Pattern group 1: it V clause
There are five patterns in this group, each consisting of it, the verb, and a type of clause:1.1 it V that
It seemed that I was right.1.2 it V to-inf
It helps to talk.1.3 it V wh
It doesn't matter what you think.1.4 it V when/if
It hurts when you forget to write.1.5 it V as if/as though/like
It sounds as if they made a dreadful mistake.