Active and Passive Voice

Active Voice In the active voice of transitive verbs (verbs that take a direct object), the subject (S) performs the action and the direct object (DO) receives the action.

S	V	DO
Sam buys gum.

S	V	DO
Lou wore blue shoes.

S	V	DO
Somebody robbed the bank.

S	V	DO
Clerks stock the shelves daily.

Passive Voice In the passive voice the subject does not perform the action of the verb; in fact, the subject receives the action. The performer of the action is placed in a prepositional phrase or is absent from the sentence.
                   S  V             PP
               Gum is bought by Sam.
                           S           V             PP
                Blue shoes were worn by Lou.
                          S          V
                 The bank was robbed.
                            S          V
                 The shelves are stocked daily.

Readers and writers often prefer the active voice because it is more direct, more emphatic, and more concise than the passive voice. Sometimes, however, the passive voice is preferable if the performer is unknown or is less important than the recipient of the action.
               S          V
        The bank was robbed.

(Passive because the identity of the robbers is unknown).
                 S           V
       The shelves are stocked daily.

(Passive because the performer of the action is unimportant).
                                               S          V               PP
        The priceless porcelain statue was broken by Kelly.

(Passive because the recipient of the action is more important than the performer).

To form the active voice of a passive verb, place the main verb in the same tense as the verb to be from the passive form. Change the subject to the direct object. To form the passive voice of an active verb, use the correct tense of the verb to be plus the past participle of the main verb.

Verb Tense Active Voice Passive Voice
Present Lou wears boots. Boots are worn by Lou.
Past My friend borrowed my car. My car was borrowed by my friend.
Future The children will share the pizza. The pizza will be shared by the children.
Present Perfect The butler has polished the silverware. The silverware has been polished by the butler.
Past Perfect Pat had sailed the boat many times. The boat had been sailed many times by Pat.
Future Perfect I will have eaten my lunch by noon today. My lunch will have been eaten by noon today.