I can see a cake.
That cake is on the desk.
I can see a pen.
That pen is in the ???.(просто не видно)
I can see a book.
That book is on the desk.
I can see two dogs.
Those dogs are under the beds.
I can see two cats.
These cats are on the??? (не вижу)
Вроде так, но должно быть правильно.