Today, Sam wrote questions and answers asking one person who everyone is. Example: Quien es? Es nuestro abuelo. (singular) / Quienes son? Son nuestros abuelos. (plural) I explain: When you want to ask who a person is, use the expression Quien es? When you want to ask who several people are, use Quienes son?...W e practiced more examples. I said "Imagine Sam, you have many people's clothes in you house. Another student asks you whose they are." Example: CAMISA/TU HERMANO. La camisa es de tu hermano? Si, es su camisa.