Are you at home=Yes,I am. I am at home.
Are you reading?=Yes,I am. I am reading.
Is it hot today?=No, it isn't. It isn't hot today.
Is your friend with you?=No, he(she) isn't. He(she) is at home.
Is your granny in the country?=Yes, she is. She is in the country.
Are your parents at the seaside?=No, they aren't. They are at work.
Are your parents working now?=Yes, they are. They are working now.