Introductory it as Subject
Pattern group 3: it V prep clausePatterns in which the preposition is to and the prepositional phrase indicates a human being have been described in Pattern group 2 above. Here we describe the patterns which contain other prepositional phrases.There are two patterns in this group, each consisting of it, the verb, a prepositional phrase, and a type of clause:
3.1 it V prep thatIt came to light that he had not been telling the truth.
3.2 it V prep to-infIt was up to me to decide what to do.