Saylor.org's English Composition/Active versus Passive Voice
Although grammatically correct, passive voice is a type of grammatical structure that, when overused, can contribute to wordiness, weak verbs, awkward phrasing, or ambiguity. The passive voice has some important stylistic functions and can be used to change the emphasis of a sentence, helping to highlight the receiver of the action or to maintain cohesion in a paragraph. At the same time, however, passive sentences often are wordier and do not sound as forceful or direct as their active-voice counterparts. Consider this example:
Catherine was fascinated by British history. (passive)
British history fascinated Catherine. (active)
Although the choice of active or passive depends on the context, we may prefer the active sentence in this instance because it expresses the action more dynamically and uses fewer words to express the exact same idea.
It is important to recognize that the passive voice is formed in English by combining the verb "to be" (or occasionally "to get") and the past participle verb form. The use of "to get" with the past participle (known as the "get-passive") is restricted to informal situations.
John got hit by the ball. (informal)
John was hit by the ball. (formal)
It is important not to confuse the passive voice with other grammatical structures, such as the past tense or the progressive aspect. For regular verbs, both the past tense and the past participle forms are the same (they both end in "-ed"), but passive sentences in the past tense contain a form of "to be" (typically "was" or "were"). It is also easy to confuse the progressive aspect for the passive voice. Both the passive and the progressive make use of "to be," but the progressive uses the present (-ing) participle.
Here are some examples:
The young man was approached by a stranger. (passive)
A stranger approached the young man. (active)
The computer is being repaired by an expert. (passive)
An expert is repairing the computer. (active)
Overusing the passive voice can make writing wordier and less interesting. Some sentences can sound very awkward or strange in the passive voice:
I saw the giraffe at the Louisville Zoo. (active)
The giraffe was seen by me at the Louisville Zoo. (passive)
In addition, the passive voice can be used dishonestly to hide the performer of the action.
Consider this famous line:
Mistakes were made.
This passive sentence, which contains an irregular past participle verb form ("made"), is constructed carefully to avoid naming the individual or individuals who made the mistakes.
Using the passive voice inappropriately can add to the problem of wordiness and rob a piece of writing of its vigor, but this is not to say that the passive does not have its place in good writing. The passive may be the better choice, for example, when the receiver of the action is the most important part of the sentence or when the performer of the action is obvious, unimportant, or unknown. Because it is possible to change the word order by changing voices, switching to the passive also can be a means of creating cohesion or adding variety and interest. We also can use the passive to emphasize the performer of the action by placing it at the end of the sentence (arguably the most emphatic part) in a "by" prepositional phrase.
David was hit by the ball. (Depending on the context, we may wish to emphasize the person instead of the physical object.)
Individuals who are lactose intolerant have trouble digesting lactose, the natural sugar found in dairy products. The lactose in milk and other foods is broken down by the enzyme lactase.... (The use of the passive makes "lactose" the subject of the sentence, keeping the emphasis on lactose and creating cohesion.)
This story was written by Charles Dickens, the novelist famous for A Christmas Carol and Oliver Twist. (Using the passive actually emphasizes the performer of the action and allows us to provide additional information about Dickens.)
The thief was arrested last night. (The agent, i.e., the police, is well known.)
These laptops are made in Taiwan. (It may not be particularly relevant in this context to mention who makes them.)
Their leader was assassinated ten years ago. (It is unknown who assassinated him.)
Converting from the passive to the active (or vice versa) is fairly straightforward. Consider this sentence:
The man was bitten by the dog. (passive)
"The man" is the subject, and "was bitten" is the verb phrase. This sentence actually does not have an object, but it does have an agentive adjunct ("the dog"). To rewrite this sentence in the active voice, first identify the agent ("the dog") and make it the subject of the sentence.
Next, find the verb or verb phrase. The use of "was" signifies the past tense, so place the active verb in the past tense ("bit").
The dog bit....
Finally, identify the receiver of the action ("the man"). Make it the object of the sentence.
The dog bit the man. (active)
Use this method to change some of your passive sentences to the active voice, which is more concise and uses the easy-to-understand subject-verb-object word order.