Yes/No questions and short answers - be

Yes/No questions - be (am, are, is)

Subject and verb change their position in statement and question.

statement	You are from Germany.
question	Are you from Germany?

We always use the short answer, not only "Yes" or "No".
NOTE:
If the answer is "Yes", we always use the long form.
Example: Yes, I am.
If the answer is "No", we either use the long or the contrated form (short form).
Example: No, I am not - No, I'm not.

Are	you	from Germany?	Yes,	I	am.
			No,	I	am not. 'm not.
Is	he	your friend?	Yes,	he	is.
Are	Peter and John	from England?	Yes,	they	are.