impersonal passive

CÂU BỊ ĐỘNG TƯỜNG THUẬT Active: S1 + say/said/… + that + S2 + V believe/believed/… think/thought/… Passive: It + to be + P2 + that + clause S2 + to be + P2 + to V (1) (2) to have + P2 (khi V dạng QK, qkht) E.g (1): The coins are believed to have been buried for safe keeping ( IT ) -> It is believed that the coins were buried for safe keeping E.g (2): Everyone thought the book was written by the princess herself (HAVE) -> The book was thought to have been written by the princess herself