Ingles, anctiva and passiva voice

Use of Passive
Passive voice is used when the focus is on the action. It is not important or not known, however, who or what is performing the action.
Example: My bike was stolen.
In the exampleabove, the focus is on the fact that my bike was stolen. I do not know, however, who did it.Sometimes a statement in passive is more polite than active voice, as the following example shows:
Example:A mistake was made.
In this case, I focus on the fact that a mistake was made, but I do not blame anyone (e.g. You have made a mistake.).
Form of Passive
Subject + finite form of to be + PastParticiple (3rd column of irregular verbs)
Example: A letter was written.
When rewriting active sentences in passive voice, note the following:
■the object of the active sentence becomes the subject ofthe passive sentence
■the finite form of the verb is changed (to be + past participle)
■the subject of the active sentence becomes the object of the passive sentence (or is dropped)
Examples ofPassive Level: lower intermediate
Tense Subject Verb Object
Simple Present Active: Rita writes a letter.
Passive: A letter is written by Rita.
Simple Past Active: Rita wrote a letter.
Passive:A letter was written by Rita.
Present Perfect Active: Rita has written a letter.
Passive: A letter has been written by Rita.
Future I Active: Rita will write a letter.
Passive: A letter willbe written by Rita.
Hilfsverben Active: Rita can write a letter.
Passive: A letter can be written by Rita.

Examples of Passive Level: upper intermediate
Tense Subject Verb Object
PresentProgressive Active: Rita is writing a letter.
Passive: A letter is being written by Rita.
Past Progressive Active: Rita was writing a letter.
Passive: A letter was being written by Rita.
PastPerfect Active: Rita had written a letter.
Passive: A letter had been written by Rita.
Future II Active: Rita will have written a letter.
Passive: A letter will have been written by Rita....