Subject Pronouns and Ser Subject Pronouns Subjects and subject pronouns are optional in Spanish, you can always use them if you are not sure. The pronoun replaces the subject The pronouns I – Yo You (familiar) – tú You (formal) – usted, Ud. He, it – él She, it – ella We – nosotros, nosotras You (plural) – ustedes, Uds. They – ellos, ellas The verb Ser (to be) Ser means to be Ser is an infinitive verb Infinitive means an unconjugated verb, a verb without a subject A conjugation of a verb means to give it a subject The verb Ser (to be) Yo Tú Usted Él Ella Nosotros –as Ustedes Ellos –as soy eres es es es somos son son I am. You are. (familiar) You are. (formal) He is. She is. We are. You (all) are. They are. The verb Ser (to be) Yo Tú Usted, él, ella Nosotros –as Ustedes, ellos -as soy eres es somos son I am. You are. (familiar) You (formal) are, he/she is. We are. You (all), they are.