* Complete Subject: The last essay question
* Complete Predicate: was really challenging
Let's explain why:
* Subject: The subject of a sentence is the person, place, thing, or idea that the sentence is about. In this case, the subject is "the last essay question."
* Predicate: The predicate tells us something about the subject. Here, it tells us that the "last essay question" was "really challenging."
Note: The word "was" is a linking verb, connecting the subject to the predicate adjective "challenging."