Does he take photographs? Yes, he does.
Is he taking a photograph? No, he isn't.
What is he doing? He's having a bath.
Is she driving a bus? Yes, she is.
Does she drive a bus? Yes, she does.
What is she doing? She is driving a bus.
Does he clean windows? Yes, he does.
Is he cleaning a window? Yes, he is.
What is he doing? He is cleaning a window.
Are they teaching? No, they aren't.
Do they teach? Yes, they do.
What do they do? They are teachers.