Where is this? Where are they? What can you see?
It's a library./ They are at the library. / I can see ....
Where are they going? Where are they? What do you see?
They are going to the library./ They're at the library./ I can see ....
Where is she going? Where is she? What is she doing?
She's going to the library. / She's at the library. / She is looking for a book.