Can a sentence have only complete subject?

No, a sentence cannot have only a complete subject. Here's why:

* Subject: The subject is the noun or pronoun that performs the action or is being described.

* Predicate: The predicate tells us what the subject does or is. It includes the verb and any other information about the subject.

A complete sentence requires both a subject and a predicate to convey a complete thought.

Examples:

* Incomplete: "The dog." (This is just a subject, missing the predicate)

* Complete: "The dog barked." (This has both the subject "dog" and the predicate "barked")

Let me know if you have any other grammar questions!