To be — explicación 

Verbo auxiliar: to be

Forma base: be

Forma presente: am/is/are

Forma pasada: was/were

Gerundio: being

Participio pasado: been

(1) Usamos el verbo auxiliar to be como verbo copulativo para conectar el adjetivo con el sujeto, esto es, usamos el verbo to be con adjetivos para describir personas o cosas. En resumen, solemos usar el verbo auxiliar to be con los adjetivos para modificar o describir nombres. Todos los diversos tipos del verbo auxiliar de to be están en el siguiente diálogo. She is smart. I am tall. David and Barry are nice. 

To be – contexto

• Sam, what do you like most about what you’re studying?
• Well, I’m studying education and for me, it’s very insightful¹, fun, and hard.
• Why did you decide to study education?
• Because it’s² required for the teaching sector. I also find it to be very practical and useful. 
• So, why would you like to be a teacher?
• I think being a teacher would be difficult but also fulfilling. Some of my friends are also studying education, and they are very excited to be following that path.
• How long have your friends been interested in education?
•  They’ve been interested in education for over three years now.

Diálogo (2)

• Hey Lucy, how’s your new job?
• It’s great, thanks. The job is very demanding but also exciting.
• I’m happy for you. How’s the boss, anyhow?
• The boss is nice, but also strict. He’s also very busy. 

To be – análisis

1.  It’s very insightful, fun and hard. Los adjetivos siendo usados con el verbo to be están en el color rojo y siempre rigen el verbo auxiliar to be u otros verbos copulativos.
2. Because it’s required for the teaching sector. Recuerda, it’s es la contracción de it is. Is es la tercera persona del singular del verbo to be.