1. A subject: This is the person, place, thing, or idea that the sentence is about. It answers the question "who?" or "what?"
2. A verb: This is the action or state of being that the subject is performing or experiencing. It answers the question "what is happening?"
Here's a simple example:
* The cat slept.
* Subject: The cat
* Verb: slept
Other things that can make a sentence complete:
* A complete thought: The sentence should express a complete idea that makes sense on its own.
* Proper grammar: The sentence should follow the rules of grammar, including word order and punctuation.
Here are some examples of incomplete sentences:
* The cat. (Missing a verb)
* Sleeping soundly. (Missing a subject)
* Because it was tired. (Not a complete thought)
Important Note: While the above is the most common definition of a complete sentence, there are some exceptions. For example, in informal writing or conversation, a sentence might be considered complete even if it lacks a subject or verb, but it's important to use proper grammar in formal writing.