Which sentence is a correct complete sentence?

• A. In the rec yard, a fight witnessed.
• B. Witnessing a fight in the rec yard.
• C. The fight witnessed by me in the rec yard.
• D. I witnessed a fight in the rec yard.

Answer: (D)

A complete sentence needs a clear subject and a finite verb that express a full thought. The form with “I witnessed a fight in the rec yard.” does this: “I” is the subject, “witnessed” is the finite verb, and “a fight in the rec yard” is the object, all together presenting a complete statement in the past tense with proper punctuation.

The other options fall short because they don’t provide a finite verb with a stated subject:

• “In the rec yard, a fight witnessed.” starts with a prepositional phrase and ends with a noun phrase, missing a main verb to form a complete thought.

• “Witnessing a fight in the rec yard.” is a participial/gerund phrase and lacks a linking subject and finite verb to stand alone as a sentence.

• “The fight witnessed by me in the rec yard.” has a noun phrase with a passive feel but no finite verb, so it’s not a complete sentence on its own.

So the sentence with a clear subject performing a finite action is the only one that expresses a complete thought.