So how do we change a sentence from active to passive?
1- We should know (Subject, Verb, Object)
2- Move the Object to the beginning.
3- Know the Tense of the active sentence. And put (Verb to Be) in that tense/time.
4- Put the main verb of active sentence in Past Participle (V3).
5- Move the Subject to the end and put "by" before it. Or you just delete is.