People believe that he is ill.改被动He is believed to be ill.怎么会出现不定式to be

Question

People believe that he is ill.改被动
He is believed to be ill.
怎么会出现不定式to be

Answer 1

He is believed to be ill.正确.
People say he has gone to London.
He is said to have gone to London.
People consider that he is writing a new novel.
He's considered to be writing a new novel.