people say/believe/think that s+v 의 수동태 전환시
= it is said/believed/thought that s+v
= s be said/believed/thought to-v 꼴로 되는건 아는데요

다음 문장은 어떻게 바꾸어 지나요?

who is believed to have been the first person to invent the printing press?
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