POSSESSIVE PRONOUNS CONJUNCTIVE.

My, mi, mis. His, su, sus. Its, su, sus.
Thy, tu, tus. Her, su, sus. Their, su, sus.
Your, with reference to Usted, or Ustedes, su, sus.

These pronouns agree in number with the noun that follows them; as, He sold his horses, él vendió sus caballos; they fulfilled their promise, ellos cumplieron, su promesa.