Short form: long form:
I'm I am
You're You are
He's He is
She's She is
It's It is
We're We are
You're You are
They're They are
to be questions and short answers:
Am I running? Yes, I am. No, I'm not.
Are you running? Yes, you are. No you aren't.
Is he running? Yes, he is. No, he isn't.
Is she running? Yes, she is. No, she isn't.
Is it running? Yes, it is. No, it isn't.