Pronouns

Reference and case.

Clear reference

Every pronoun should point at one obvious noun. If a sentence offers two candidates, repeat the noun rather than leaving the reader to guess.

Vague this and it at the start of a sentence are common and unclear.
A pronoun must match its noun in number: each employee brought their pass is now standard.

Subject forms are I, he, she, they, who. Object forms are me, him, her, them, whom. After a preposition, use the object form: between you and me.