এটা হল কমপ্লেক্স ও কম্পাউন্ড সেন্টেন্সের ভয়েস চেঞ্জ। in complex or compound both the cluses (if both the cluses have transitive verb) should be transformed into passive. by the rule:----- active :- he said that he made the mistake. passive :- That the mistake was made by him was said by him. এরকম আরেকটা হল I know that he did the work. pass:- That the work was done by him is known to me.