Question

comó se sabe si en una frase se debe poner has got o have got o el berbo to be porfavor mañana tengo un examen

Answer 1

Usas Have para : I, You
Has para = She, He, it
(solo en presente)

lo del verbo to be => http://www.aprenderinglesfacil.es/2008/03/verbo-to-be-ser-o-estar.html 

Answer 2

HAS es para tercera persona del singular

She o He se ponen con HAS, las demás HAVE ; Significa "tener".

I HAVE
You HAVE
He / She HAS
We HAVE
You HAVE (es igual tú que vosotros)
They HAVE

El verbo TO BE significa "ser o estar" y es distinta la primeray tercera persona:

I AM

You ARE

He / She IS

We ARE

You ARE (se dice igual TÚ que VOSOTROS)

They ARE

Espero que te sirva, ¡ suerte !