Apostrophe with indefinite pronouns

An apostrophe with -s is used to show possession with indefinite pronouns such as everyone, someone, no one, and something.

Example sentence: Someone's raincoat has been left behind.

Example sentence: Reducing groundwater pollution is in everyone's best interest.

Exercise: The apostrophe 1

Exercise: The apostrophe 2

Related topic:

Possessive pronouns

indefinite pronoun A pronoun that refers to a nonspecific person or thing: anyone, nobody, everything.