1. ... is it? — It is, actually. But it looks cozy.
2. ... can you? — Yes you can. There are three desks in this picture.
3. ... aren't there? — No, there are only three pupils in the classroom.
4. ... is there? — No, there is a teacher in the classroom.
5. ... aren't they? — No, they are standing.
6. ... is she? — No, she isn't writing at the blackboard.