In sentences written in active voice, the subject performs the action expressed in the verb; the subject acts.
~I broke the window.
~The boys ate all of the pie.
~With the money from her mother's life insurance Diane
bought a new car and took a trip to Europe.
In each example above, the subject of the sentence performs the action expressed in the verb.
In sentences written in passive voice, the subject receives the action expressed in the verb; the subject is acted upon. The agent performing the action may appear in a "by the . . ." phrase or may be omitted.
~The window was broken.
~The window was broken by me.
~All of the pie was eaten.
~All of the pie was eaten by the boys.
~With the money from her mother's life insurance a new car was bought and a trip to Europe was taken.
~With the money from her mother's life insurance a new car was bought
and a trip to Europe was taken by Diane.
Sometimes the use of passive voice can create awkward sentences, as in the last example above. Also, overuse of passive voice throughout an essay can cause your prose to seem flat and uninteresting. In scientific writing, however, passive voice is more readily accepted since using it allows one to write without using personal pronouns or the names of particular researchers as the subjects of sentences. This practice helps to create the appearance of an objective, fact-based discourse because writers can present research and conclusions without attributing them to particular agents. Instead, the writing appears to convey information that is not limited or biased by individual perspectives or personal interests.
You can recognize passive-voice expressions because the verb phrase will always include a form of be, such as am, is, was, were, are, or been. The presence of a be-verb, however, does not necessarily mean that the sentence is in passive voice. Another way to recognize passive-voice sentences is that they may include a "by the..." phrase after the verb; the agent performing the action, if named, is the object of the preposition in this phrase.
Choosing Active Voice
In most nonscientific writing situations, active voice is preferable to passive for the majority of your sentences. Even in scientific writing, overuse of passive voice or use of passive voice in long and complicated sentences can cause readers to lose interest or to become confused. Sentences in active voice are generally--though not always-- clearer and more direct than those in passive voice.
Sentences in active voice are also more concise than those in passive voice because fewer words are required to express action in active voice than in passive.
Changing Passive to ActiveTo change passive voice to active, identify the performer of the action. If the performer is in a "by the" phrase, move the performer to the subject position, just before the verb. If the writer did not name a performer, choose a subject that fits the context. "The test results will be announced next week" easily becomes "We will announce the test results next week" or "The researchers will announce the test results next week."
Avoid mixing active and passive voice in the same sentence. The first half of this sentence is active, but the second half is passive: "We found the lost contract, and the client was notified immediately." Instead, use active voice throughout: "We found the lost contract and notified the client immediately."
Choosing Passive Voice
While active voice helps to create clear and direct sentences, sometimes writers find that using an indirect expression is rhetorically effective in a given situation, so they choose passive voice. Also, as mentioned above, writers in the sciences conventionally use passive voice more often than writers in other discourses. Passive voice makes sense when the agent performing the action is obvious, unimportant, or unknown or when a writer wishes to postpone mentioning the agent until the last part of the sentence or to avoid mentioning the agent at all. The passive voice is effective in such circumstances because it highlights the action and what is acted upon rather than the agent performing the action.
|The dispatcher is notifying police that three prisoners have escaped.||Police are being notified that three prisoners have escaped.|
|Surgeons successfully performed a new experimental liver-transplant operation yesterday.||A new experimental liver-transplant operation was performed successfully yesterday.|
"Authorities make rules to be broken," he said defiantly.
|"Rules are made to be broken," he said defiantly.|
In each of these examples, the passive voice makes sense because the agent is relatively unimportant compared to the action itself and what is acted upon.
Changing active to passive
If you want to change an active-voice sentence to passive voice, consider carefully who or what is performing the action expressed in the verb, and then make that agent the object of a "by the..." phrase. Make what is acted upon the subject of the sentence, and change the verb to a form of be + past participle. Including an explicit "by the..." phrase is optional.
Avoid starting a sentence in active voice and then shifting to passive.
|Unnecessary shift in voice||Revised|
|Many customers in the restaurant found the coffee too bitter to drink, but it was still ordered frequently.||Many customers in the restaurant found the coffee too bitter to drink, but they still ordered it frequently.|
|He tried to act cool when he slipped in the puddle, but he was still laughed at by the other students.||He tried to act cool when he slipped in the puddle, but the other students still laughed at him.|
Don't trust the grammar-checking programs in word-processing software. Many grammar checkers flag all passive constructions, but you may want to keep some that are flagged. Trust your judgement, or ask another human being for their opinion about which sentence sounds best.Sources: here and here