Question

A weak or indefinite reference occurs when a pronoun

Answer 1

example:
Indefinite: When the play begins, *they* don't let late-comers in until the end of the first act.
(We do not know who won't let them in.)
Correct: When the play begins, the *ushers* don't let late-comers in until the end of the first act.

What is the difference between the pronouns here?