1. Active and Passive Voice
Sometimes the use of passive voice can create awkward sentences.
Also, overuse of passive voice throughout an essay can cause your writing to seem flat and uninteresting.
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.
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.

2. You can recognize passive voice expressions because the verb phrase will always include a form of “be” (such as am, is, was, were, are or been).
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.
In a sentence using active voice, the subject of the sentence performs the action expressed in the verb.
The dog jumped onto the boy.
Kristy will give a book report to the class.
The computer ate my paper.

3. More Examples: Passive: Active: 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.
The brakes were slammed on by her as the truck came toward her.
Notice that this is an awkward sentence?
She slammed on her brakes as the truck came toward her.
The medicine was given to me by the vet.
The vet gave me the medicine.