SENTENCE is in the Active voice, as the form of the VERB (‘attend’) shows that its subject was doing something and was ‘active’.Therefore, it MUST be changed to the Passive voice, where something could be done by the subject, and it was ‘passive’.In order to do that,1. The object of the transitive verb in the Active voice should become the subject of the verb in the Passive voice.2. Add the appropriate form of the verb 'be' to the sentence and use the past participle of the verb (‘attend’ is CONVERTED to ‘attended’).3. Add a 'by' followed by the doer of the action.Thus, the same sentence in the Passive voice is ‘Are the daily SERMONS attended by Peter and John?’