Complete the defining clause by omitting the object relative pronoun: The atlas ___ is on the desk. Use exactly the subject we, the simple-past verb borrowed, and the adverb yesterday in that order, with no added words.

Explication

We is the subject of borrowed, while the atlas supplies its understood object, so an object contact clause is grammatical. Inserting an extra it would be the closest error because the antecedent already fills that object role.