missss vittttaa...:D

"Passive  Voices"

Verbs are also said to be either active (The executive committee approved the new policy) or passive (The new policy was approved by the executive committee) in voice. In the active voice, the subject and verb relationship is straightforward: the subject is a be-er or a do-er and the verb moves the sentence along. In the passive voice, the subject of the sentence is neither a do-er or a be-er, but is acted upon by some other agent or by something unnamed (The new policy was approved).
Take the quiz (below) as an exercise in recognizing and changing passive verbs.
The passive voice does exist for a reason, however, and its presence is not always to be despised. The passive is particularly useful (even recommended) in two situations:

• When it is more important to draw our attention to the person or thing acted upon: The unidentified victim was apparently struck during the early morning hours.
• When the actor in the situation is not important: The aurora borealis can be observed in the early morning hours.

 Passive Verb Formation

Tense	Subject	Auxiliary		Past Participle
		Singular	Plural
Present	The car/cars	is	are	designed.
Present perfect	The car/cars	has been	have been	designed.
Past	The car/cars	was	were	designed.
Past perfect	The car/cars	had been	had been	designed.
Future	The car/cars	will be	will be	designed.
Future perfect	The car/cars	will have been	will have been	designed.
Present progressive	The car/cars	is being	are being	designed.
Past progressive	The car/cars	was being	were being	designed.

Active	Professor Villa gave Jorge an A.
Passive	An A was given to Jorge by Professor Villa.
Passive	Jorge was given an A.

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.

sumber :  http://grammar.ccc.commnet.edu/grammar/passive.htm