"He goes to school."
This sentence cannot be changed from active voice to passive voice, but it can be changed from a simple tense verb form to a perfect tense. It's a tricky situation because perfect tense verbs are used to make passive voice sentences. So, all of us eager grammarians actually have to look thoughtfully at the meaning of the words to figure out if the sentence structure has changed.
You probably know this, but I'll explain anyway in case someone else needs help. Active voice simply means that whatever word that represents the subject of the sentence (a person, idea, thing, place, or pronouns to represent these items also) is active. The subject is doing whatever action the verb describes. In passive voice, another part of the sentence, usually the direct object, is moved to the spot in the structure of the sentence that the subject occupies.
Active voice = subject acting out verb
Passive voice = subject is being acted upon by the verb
Here's an example:
Active voice: Fakpak enters data on a computer.
[subject] [verb] [d.o] [prepositional phrase]
Passive voice: Data is entered by Fakpak on a computer.
The meaning in both is exactly the same. A person is entering information on a computer. They're both in present tense still ("is entered" present perfect; "was entered" past perfect), which is an important mistake to watch out for and to avoid.
So, if a question on a test asks you about active or passive voice, you should look at the sentence structure. Perfect tense verb forms are tools used to show passive voice, but they have other uses also. Don't assume that a helping verb/auxillary verb automatically guarantees passive voice.
Let me know if you want an explanation on why a writer would choose a specific voice for a specific situation.
Hope I helped!
- For Teachers