He IS / ISN'T an artist
IS
She IS / ISN'T an artist.
IS
ARTIST
He is an artist
He IS/ISN'T a doctor.
ISN'T
He IS / ISN'T a farmer.
ISN'T
FARMER
He isn't a farmer.
He IS / ISN'T a farmer.
IS
TEACHER
She isn't a teacher.
He IS/ISN'T a farmer.
ISN'T
DOCTOR
He is a doctor
He IS/ISN'T an artist.
ISN'T
COOK
he is a cook
ARTIST
She is an artist.
She IS / ISN'T a vet.
ISN'T
VET
She isn't a vet
He IS / ISN'T a teacher.
IS
She IS / ISN'T a vet.
ISN'T
TEACHER
She is a teacher.