Active and Passive Voice

Active Voice
Active voice is a grammatical voice common in many of the world's languages. It is the unmarked voice for clauses featuring a transitive verb in nominative–accusative languages, including English and most other Indo-European languages. Active voice is used in a clause whose subject expresses the agent of the main verb. That is, the subject does the action designated by the verb.

A sentence whose agent is marked as grammatical subject is called an active sentence. In contrast, a sentence in which the subject has the role of patient or theme is named a passive sentence, and its verb is expressed in passive voice. Many languages have both an active and a passive voice; this allows for greater flexibility in sentence construction, as either the semantic agent or patient may take the syntactic role of subject. 

In most English sentences with an action verb, the subject performs the action denoted by the verb. Because the subject does or "acts upon" the verb in such sentences, the sentences are said to be in the active voice. The active voice is the most commonly used in many languages and represents the "normal" case, in which the subject of the verb is the agent. In the active voice the subject of sentence performs the action or causes the happening denoted by the verb.

Why is the Active Voice So Important?

If you’ve ever had a go at creative writing, you’ll probably have come across the advice to always write in the active voice. This is a good rule of thumb for most pieces of fiction: sentences in the active voice have energy and directness, both of which will keep your reader turning the pages. Sentences written in the active voice are also less wordy than those in the passive voice – and cutting unnecessary words always improves a piece of writing, whether it’s fiction or non-fiction.

Students writing academic essays can sometimes tie themselves in knots trying to make sentences sound “formal” – which often (mistakenly) is taken to mean putting a sentence in the passive voice. 

Tips and Tricks for Using the Active Voice

Use the active voice when you want your writing to be simple, direct, clear and easy to read. If you’re not very confident about your writing, using the active voice can be an easy way to improve a dull or lifeless piece of prose. However, don’t make the mistake of thinking that you always need to use the active voice. Sometimes, it’s perfectly appropriate to phrase a sentence in the passive voice.

Examples of Active Voice

Here are examples of sentences written in the active voice:

1.      Harry ate six shrimp at dinner.
2.      Beautiful giraffes roam the savannah.
3.      Sue changed the flat tire.
4.      We are going to watch a movie tonight.
5.      I ran the obstacle course in record time.
6.      The crew paved the entire stretch of highway.
7.      Mom read the novel in one day.
8.      The critic wrote a scathing review.
9.      I will clean the house every Saturday.
10.  The staff is required to watch a safety video every year.

Passive Voice

Passive voice is a grammatical voice common in many of the world's languages. In a clause with passive voice, the grammatical subject expresses the theme or patient of the main verb – that is, the person or thing that undergoes the action or has its state changed. This contrasts with active voice, in which the subject has the agent role.

Typically, in passive clauses, what would otherwise be expressed by the object (or sometimes another argument) of the verb comes to be expressed by the subject, while what would otherwise be expressed by the subject is either not expressed at all, or is indicated by some adjunct of the clause. Thus transforming an active verb into a passive verb is a valence-decreasing process ("detransitivizing process"), because it transforms transitive verbs into intransitive verbs. This is not always the case; for example in Japanese a passive-voice construction does not necessarily decrease valence.

Many languages have both an active and a passive voice; this allows for greater flexibility in sentence construction, as either the semantic agent or patient may take the syntactic role of subject. The use of passive voice allows speakers to organize stretches of discourse by placing figures other than the agent in subject position. This may be done to foreground the patient, recipient, or other thematic role; it may also be useful when the semantic patient is the topic of on-going discussion. The passive voice may also be used to avoid specifying the agent of an action.

The term passive is applied to a wide range of grammatical structures and is therefore difficult to define. The canonical passive in European languages has the following properties:

1. non-agentive subject
2. change in constituent order or nominal morphology
3. specific verbal morphology

The problem arises with non-European languages. Many constructions in these languages share at least one property with the canonical European passive, but not all. While it seems justified to call these constructions passive when comparing them to European languages' passive constructions, as a whole the passives of the world's languages do not share a single common feature. 

R. M. W. Dixon has therefore defined four criteria for determining whether a construction is a passive:

1. It applies to underlying transitive clauses and form a derived intransitive.
2. The underlying O becomes S.
3. The underlying A goes into the periphery and is marked by a non-core case/preposition/etc. This can be omitted, but there's always the option of including it.
4. There is some explicit marking of the construction.

He acknowledges that this excludes some constructions labeled as passive by some linguists.

Form of Passive

Subject + finite form of to be + Past Participle (3rd column of irregular verbs)
When rewriting active sentences in passive voice, note the following:

• the object of the active sentence becomes the subject of the passive sentence
• the finite form of the verb is changed (to be + past participle)
• the subject of the active sentence becomes the object of the passive sentence (or is dropped)

Verbals in Passive Structures

Verbals or verb forms can also take on features of the passive voice. An infinitive phrase in the passive voice, for instance, can perform various functions within a sentence (just like the active forms of the infinitive).

• Subject: To be elected by my peers is a great honor.
• Object: That child really likes to be read to by her mother.
• Modifier: Grasso was the first woman to be elected governor in her own right.

The same is true of passive gerunds.

• Subject: Being elected by my peers was a great thrill.
• Object: I really don't like being lectured to by my boss.
• Object of preposition: I am so tired of being lectured to by my boss.

With passive participles, part of the passive construction is often omitted, the result being a simple modifying participial phrase.

• [Having been] designed for off-road performance, the Pathseeker does not always behave well on paved highways.

Passive Verb Formation

The passive forms of a verb are created by combining a form of the "to be verb" with the past participle of the main verb. Other helping verbs are also sometimes present: "The measure could have been killed in committee." The passive can be used, also, in various tenses. Let's take a look at the passive forms of "design."
















A sentence cast in the passive voice will not always include an agent of the action. For instance if a gorilla crushes a tin can, we could say "The tin can was crushed by the gorilla." But a perfectly good sentence would leave out the gorilla: "The tin can was crushed." Also, when an active sentence with an indirect object is recast in the passive, the indirect object can take on the role of subject in the passive sentence:








 
Only transitive verbs (those that take objects) can be transformed into passive constructions. Furthermore, active sentences containing certain verbs cannot be transformed into passive structures. To have is the most important of these verbs. We can say "He has a new car," but we cannot say "A new car is had by him." We can say "Josefina lacked finesse," but we cannot say "Finesse was lacked." Here is a brief list of such verbs*:

  





Examples of Passive Voice
 
Here are examples of sentences written in the active voice:

1. At dinner, six shrimp were eaten by Harry.
2. The savannah is roamed by beautiful giraffes.  
3. The flat tire was changed by Sue.
4.  A movie is going to be watched by us tonight.
5. The obstacle course was run by me in record time.
6. The entire stretch of highway was paved by the crew.
7. The novel was read by Mom in one day.  
8. A scathing review was written by the critic.
9. The house will be cleaned by me every Saturday.
10. A safety video will be watched by the staff every year.

Personal and Impersonal Passive

Personal Passive simply means that the object of the active sentence becomes the subject of the passive sentence. So every verb that needs an object (transitive verb) can form a personal passive.

Example: They build houses. – Houses are built.

Verbs without an object (intransitive verb) normally cannot form a personal passive sentence (as there is no object that can become the subject of the passive sentence). If you want to use an intransitive verb in passive voice, you need an impersonal construction – therefore this passive is called Impersonal Passive.

Example: he says – it is said

Impersonal Passive is not as common in English as in some other languages (e.g. German, Latin). In English, Impersonal Passive is only possible with verbs of perception (e. g. say, think, know).

Example: They say that women live longer than men. – It is said that women live longer than men.

Although Impersonal Passive is possible here, Personal Passive is more common.

Example: They say that women live longer than men. – Women are said to live longer than men.

The subject of the subordinate clause (women) goes to the beginning of the sentence; the verb of perception is put into passive voice. The rest of the sentence is added using an infinitive construction with 'to' (certain auxiliary verbs and that are dropped).

Sometimes the term Personal Passive is used in English lessons if the indirect object of an active sentence is to become the subject of the passive sentence.




References:
http://grammar.ccc.commnet.edu/grammar/passive.htm
http://examples.yourdictionary.com/examples/examples-of-active-and-passive-voice.html 
http://www.ego4u.com/en/cram-up/grammar/passive
http://www.towson.edu/ows/activepass.htm
http://en.wikipedia.org/wiki/Active_voice
http://en.wikipedia.org/wiki/Passive_voice
http://en.wikipedia.org/wiki/Voice_%28grammar%29
http://www.dailywritingtips.com/active-voice/