He could be either one, depending on the context.
Do you have this sentence in a whole paragraph?
Hello, Dr. Green.
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In this expression, is Dr. Green a doctor who works at a hospital? Or is Dr. Green a professor in college?
2 answers
what is the subject and what is the predicate, of the following sentence.
The driver of the pickup truck backed into my car and then sped away.
The driver of the pickup truck backed into my car and then sped away.