Here's why:
* Subject: The subject is the person or thing performing the action of the verb.
* Verb: The implied verb in the sentence is "is" or "was" (as in "The man is standing on the corner near a policeman").
* Object: The object is the person or thing receiving the action of the verb. In this case, it's unclear who or what the object is because the sentence is incomplete.
While "policeman" could be considered the subject, it's more likely a prepositional phrase describing the location of the man.