Verbs in the active voice have the performer of the action as the subject and have the person or thing that is acted upon as the object. Thus the sentences Marty found the kitten under the couch and The girls built a house of blocks today have their verbs in the active voice. In the passive voice this situation is reversed. The person or thing that is acted upon becomes the subject, and the performer of the action gets put in a prepositional phrase beginning with by or is omitted from the sentence altogether. 2 Passive verb phrases normally consist of a form of the verb be followed by a past participle.
Passive verbs can exist in any tense.
They may or may not employ an auxiliary verb. Active Passive Linda drives the car. The car is driven by Linda. Linda drove the car. The car was driven by Linda.