Anglès per a principiants. Carlos Mirasierras
Present tense of "to be" (ser o estar):
To be present tense (ser o estar) Negative form

Interrogative

I am / I'm (soy/estoy)
you are / you're (eres/estás)
he is / h'es (es/está)
we are (we're (somos/estamos)
you are / you're (sois/estais)
they are / they're (son/están)

Am I?
Am I not?
Are you?
Are you not? (arent' you?)
Is he/she/it?
Is he not (isn't he?)
Are we?
Are we not? (aren't we?)
Are you (both)? Are you not ((aren't you?)
Are they?
Are they not (aren't they?)

I am not (I'm not / I ain't)
You are not (aren't)
He is not (isn't)
We are not (aren't)
You both are not (aren't)
They are not (aren't)

Interrogative negative

To be in present continuous

It is someone who:

I am / I'm being (estoy siendo)
You're being (estás siendo)
He's being (está siendo)
We're being (estamos siendo)
You're being (estais siendo)
They're being (están siendo)

It's him who is at the door: Es él quien está en la puerta.
It's us who have to apologize: Somos nosotros los que (quienes)
han de disculparse.
It's them who are afraid of flying: Son ellos los que (quienes)
tienen miedo a volar (de volar)

Examples to be learned and memorized (Ejemplos a/para aprender y memorizar)
Affirmative:
I am / I'm in the room. The room is painted in white.
You're inside the house, not outside it.
He is interested in that car because the price is good.
She's in another world; she's in love.
It's white in color/colour but the paint is bad.
We are a group of students who are on a journey to Europe, not customers.
You both are on the list of missing people.
They are in the supermarket/grocery now with some friends from England.
Negative:
I am not / I'm not here, because I'm there.
You are not / you're not / you aren't French; you're British.
He's not from Germany, he's from Sweden.
She's not angry, she's very busy only.
We aren't students, we are waiting for a bus.
You both aren't on Facebook.
They aren't nearby, they left 2 hours ago.
Interrogative:
4