VERBO TO BE,

TO BE [=ser, estar…]
Como todos los verbos auxiliares, para hacer la negativa se le añade NOT y para la interrogativa basta con cambiar el orden (en lugar de Sujeto + Verbo, ponemos Verbo + Sujeto).

Simple Present

I am (I'm) You are (You're) He/She/It is (He's/ she's/ It's) We are (We're) You are (You're) They are (They're)

I'm not You aren't He/she/it isn't We aren't You aren't They aren't

Am I? Are you? Is he/she/it? Are we? Are you? Are they?

Simple Past

I was You were He/She/It was We were You were They were

I wasn't You weren't He/She/It wasn't We weren't You weren't They weren't

Was I? Were you? Was he/she/it? Were we? Were you? Were they?

THERE BE [=haber impersonal: "hay", "había"…]
Simple Present

There is There are

There isn't There aren't

Is there? Are there?

Simple Past

There was There were

There wasn't There weren't

Was there? Were there?

Nota: funciona igual que el verbo TO BE, pero colocando el pronombre impersonal «there» como sujeto, tanto en tiempos compuestos:
"There has been enough money"
como con verbos modales:
"There must be a reason".