VERBO TO BE - PRESENTE E PASSADO

O verbo to be ("ser" ou "estar", de acordo com o contexto) é bem conhecido, no entanto, ainda há muita gente que se confunde.

A confusão acontece porque trata-se de um verbo diferente, especial. Ele não aceita as regras que se aplicam a outros verbos, nem no presente, nem no passado. 

A mais importante é que ele não aceita auxiliares, nem na negativa, nem na interrogativa. Além disso, ele se modifica drasticamente de acordo com o sujeito. 

Confira as tabelas:

PRESENTE

AFFIRMATIVE	NEGATIVE	INTERROGATIVE	INT/NEG
I AM	I AM NOT	AM I?	AM I NOT?
YOU ARE	YOU AREN’T	ARE YOU?	AREN’T YOU?
HE IS	HE ISN’T	IS HE?	ISN’T HE?
SHE IS	SHE ISN’T	IS SHE?	ISN’T SHE?
IT IS	IT ISN’T	IS IT?	ISN’T IT?
YOU ARE	YOU AREN’T	ARE YOU?	AREN’T YOU?
THEY ARE	THEY AREN’T	ARE THEY?	AREN’T THEY?
WE ARE	WE AREN’T	ARE WE?	AREN’T WE?

PASSADO

AFFIRMATIVE	NEGATIVE	INTERROGATIVE	INT/NEG
I WAS	I WASN'T	WAS I?	WASN'T I?
YOU WERE	YOU WEREN'T	WERE YOU?	WEREN'T YOU?
HE WAS	HE WASN'T	WAS HE?	WASN'T HE?
SHE WAS	SHE WASN'T	WAS SHE?	WASN'T SHE?
IT WAS	IT WASN'T	WAS IT?	WASN'T IT?
YOU WERE	YOU WEREN'T	WERE YOU?	WEREN'T YOU?
THEY WERE	THEY WEREN'T	WERE THEY?	WEREN'T THEY?
WE WERE	WE WEREN'T	WERE WE?	WEREN'T WE?