Final answer:
A simple sentence is a complete sentence that consists of a subject and a verb and expresses a complete thought. A fragment is an incomplete sentence that does not express a complete thought. In the given examples, 'I sold it to Julie.' is a simple sentence, whereas 'Because I could.' is a fragment.
Step-by-step explanation:
A simple sentence is a complete sentence that consists of a subject and a verb and expresses a complete thought. It can stand alone as a sentence. For example, 'I sold it to Julie.' is a simple sentence because it has a subject ('I') and a verb ('sold') and expresses a complete thought.
A fragment, on the other hand, is an incomplete sentence that does not express a complete thought. Fragments often lack a subject or a verb, or they may be dependent clauses that cannot stand alone as sentences. For example, 'Because I could.' is a fragment because it lacks a verb and does not express a complete thought.
In the given examples, 'I sold it to Julie.' is a simple sentence, whereas 'Because I could.' is a fragment.
Learn more about simple sentences vs. fragments