Affirmative:
* I am
* he/she/it is
* you/we/they are
Negative:
* I'm not
* he/she/it isn't
* you/we/they aren't
Interrogative:
* Am I?
* Is he/she/it?
* Are you/we/they?
Short answers:
* Yes, I am. / No, I'm not.
* Yes, he/she/it is. / No, he/she/it isn't.
* Yes, you/we/they are. / No, you/we/they aren't.