active/passive voice

Active and Passive Voice
What is the difference between active and passive voice?
In a sentence using active voice, the subject of the sentence performs the action expressed in the verb. Examples:
The dog jumped onto the boy.
Kristy will give a book report to the class.
The computer ate my paper.
In a sentence using passive voice, the subject is acted upon; he or she receives the action expressed by the verb.Examples:
The boy was jumped on by the dog.
A book report will be given by Kristy to the class.
My paper was eaten by the computer.
Helpful Hint: You can recognize passive voice because the verb phrase will include a form of be (was, am, are, been, is). Don't assume that just because there is a form of 'be' that the sentence is passive, however. Sometimes a prepositional phrase like "by the" in the sentences above indicates that the action is performed on the subject, and that the sentence is passive.

When to choose active voice?
Active voice is used for most non-scientific writing. Using active voice for the majority of your sentences makes your meaning clear for readers, and keeps the sentences from becoming too complicated or wordy. Even in scientific writing, too much use of passive voice can cloud the meaning of your sentences.Passive:
The car was driven into the tree.
Notice that this sentence doesn't say who was driving?Active:
The thieves drove the car into the tree.Passive:
The brakes were slammed on by her as the truck came toward her.
Notice that this is an awkward sentence?Active:
She slammed on her brakes as the truck came toward her.
Active voice can also make your writing more concise, allowing you to get your point across using fewer words than you might by using passive voice. Passive:
The medicine was given to me by the vet.Active:
The vet gave me the medicine.
How do I change a sentence from passive to active voice?
It's easy! Ask yourself who or what is performing the action in the sentence (the agent). If it isn't specified, you may have to infer from context clues in the sentence or in surrounding sentences. Then, make the agent the subject of the new sentence. Don't forget to change your verb to match your new subject.

Passive:
The room is being used by most of the group.Active:
Most of the group is using the room.
In the first sentence, the subject is the room, although it is not performing an action. In the second sentence, the group is the subject and performs the action of using the room. Passive:
Mistakes were made in my research. Active:
I made mistakes in my reasearch.
In the first sentence, the agent, the person who made the mistakes, is not mentioned. In the second, the agent who performed the action of making mistakes is named.

When to choose passive voice?
Passive voice is used in scientific writing and is also useful when a writer needs to say something indirectly. When the agent is obvious, unimportant, or just unknown, writers use passive voice. Sometimes, writers prefer passive voice because they wish to postpone or to avoid mentioning the agent at all, or because they wish to highlight the action instead of the agent