There are two basic rules for converting sentences from Active Voice into Passive Voice, which are common for all tenses.
The places of subject and object will be interchanged in the sentence.
Only 3rd form of the verb or Past Participle (e.g. written) will be used as the main verb in Passive Voice.
The rules for using ‘Auxiliary Verb’ in a sentence are different for each tense, as follows:
