What I did: I read from this article the difference of active and passive voice and when to use passive and active voices.
What I learnt:
In active sentences, the doer of the action is called the subject, while the one experiencing the action is the object. Two examples of active sentences are "The professor teaches the students." and "John washes the dishes." In this two examples, "the professor" and "John" are the subjects, "teaches" and "washes" are the verbs and "the students" and "the dishes" are the objects of the sentences. Active voices are commonly used in all forms of writing.
In passive sentences, the receiver of the action is the subject while the doer of the action is the object. Two examples of passive sentences are "The students are taught by the professor." and "The dishes are washed by John." In this two examples, "the students" and "the dishes" are the subjects, "are taught" and "are washed" are the verbs and "by the professor" and "by John" are the objects of the sentences. The passive voice is often used when the author wants to place emphasis on the subject, instead of the doer of the action. Although passive is not commonly used in writing, the passive voice is used more in mystery and crime writing and reportage, whereby the doer of the action is not or cannot be known.