In questions that use Is or Are, it is possible to give short answers as follows. Always use this form to when asking questions with the verb "to be":
Are / Is + noun + rest of the sentence
Am I early?
- Yes you are.
- No you're not.
Are you busy?
- Yes I am.
- No I'm not.
Are we suppose to study tonight?
- Yes we are.
- No we're not.
Are they hungry?
- Yes they are.
- No they're not.
Is he late again?
- Yes he is.
- No he's not.
Is she home?
- Yes she is.
- No she's not.
Is it going to rain today?
- Yes it is.
- No it's not.