I am a teacher. I teach.
I am not a doctor. I do not bandage cuts.
POSITIVE NEGATIVE
am am not .... I'm not
is is not (isn't) .... She's not He's not It's not
are are not (aren't) .... We're not They're not
ACTION VERBS are different....
I/you/we/they (action) do not (action)
He/she/it (action)s does not (action)