Active Voice

Active Voice, Passive Voice
There are two special forms for verbs called voice:
1. Active voice
2. Passive voice
The active voice is the "normal" voice. This is the voice that we use mostof the time. You are probably already familiar with the active voice. In the active voice, the object receives the action of the verb:
active | subject | verb | object |
|   | > |
| Cats |eat | fish. |
The passive voice is less usual. In the passive voice, the subject receives the action of the verb:
passive | subject | verb | object |
| < |   |
| Fish | are eaten | by cats.|
The object of the active verb becomes the subject of the passive verb:
  | subject | verb | object |
active | Everybody | drinks | water. |
passive | Water | is drunk | by everybody. |What is passive voice?
In English, all sentences are in either "active" or "passive" voice:
active: Werner Heisenberg formulated the uncertainty principle in 1927.
passive: The uncertainty principlewas formulated by Werner Heisenberg in 1927.
In an active sentence, the person or thing responsible for the action in the sentence comes first. In a passive sentence, the person or thing acted oncomes first, and the actor is added at the end, introduced with the preposition "by." The passive form of the verb is signaled by a form of "to be": in the sentence above, "was formulated" is in passivevoice while "formulated" is in active.
In a passive sentence, we often omit the actor completely:
The uncertainty principle was formulated in 1927.
When do I use passive voice?
In some sentences,passive voice can be perfectly acceptable. You might use it in the following cases:
1. The actor is unknown:
The cave paintings of Lascaux were made in the Upper Old Stone Age. [We don't know whomade them.]
2. The actor is irrelevant:
An experimental solar power plant will be built in the Australian desert. [We are not interested in who is building it.]
3. You want to be vague...