Number agreement

Pronouns either replace or refer back to a noun. Accordingly, they must agree in number with the noun to which they refer or are replacing.

• Use a singular pronoun to replace a singular noun
  • The cat climbed the tree but it stopped at the top branch.
    ("cat" is singular; "it" is also singular)
  • Remember that "everyone", "someone", "anyone", "each", "neither", "nobody", "someone", "a person", etc. are singular nouns; therefore, they require a singular pronoun
    • Everyone should buy his or her bus pass.
      ("Everyone" is singular; "his" and "her" are also singular)
    • Note: "their" is a plural pronoun and is therefore incorrect when used to replace a singular noun

• Use a plural pronoun to replace a plural noun
  • The cats climbed the tree but they stopped at the top branch.
    ("cats" is plural; "they" is also plural)

(Adapted from The OWL at Purdue: Using Pronouns Clearly)