[duaneb]

> Grammatically, the passive voice also places the active participant as an explicit indirect object rather than the subject. A sentence without an explicit indirect object is not in the passive voice.

This is not true. Something as simple as "I was sat on" illustrates this well—in English, the subject is still required but the actor is not. This is much MORE so for eg Latin, where verbs take voices with much less context.

"I was exhausted" is ambiguous, using either the imperfect passive voice or the imperfect "to be" with a past participle. However, it's perfectly valid to note as passive as it is, in fact, passive under one of the two interpretations.