THERE IS = (hay - singular)
THERE ARE = (hay - plural)
Hay doce chicas en esta habitación
- There are twelve girls in this room.
- There are not twelve girls in this room.
- Are there twelve girls in this room?
Hay un libro sobre aquella mesa
- There is a book on that table
- There is not a book on that table
- Is there a book on that table?