what pronoun substitutes the noun -person- for this sentence, please:
ie: when a person sees something, x[the person] should call the police.
what pronoun substitutes the noun -person- for this sentence, please:
ie: when a person sees something, x[the person] should call the police.
Typically, it's ('singular') they. It's not everywhere accepted, so in some manuals 'he or she' is recommended instead, especially for formal usage.