Final answer:
The sentence 'Many people work long and hard for their money.' has a simple sentence structure because it contains one main clause that expresses a complete thought.
Step-by-step explanation:
The sentence structure of the sentence "Many people work long and hard for their money." is a simple sentence. This is because it contains a single main clause with one idea. A main clause includes both a subject and a predicate and has the ability to stand alone as a complete sentence. The sentence in question has a subject ('Many people') and a predicate ('work long and hard for their money'), and it expresses a complete thought without the help of additional clauses.