1. SITUATIONS IN TIME OR SPACE
   1. Está lloviendo. It's raining.
   2. Estaba lloviendo. I was raining.
   3. Estará lloviendo. It will be raining.
2. STATES IN TIME OR SPACE
   1. (Ella) está triste hoy. She's sad today.
   2. (Ella) estaba triste ayer. She was sad yesterday.
   3. (Ella) estará triste mañana. She will be sad tomorrow.