The witness was thought to have been injured.
⇒ It was thought that the witness had been injured.
The witness was thought to have been injured.
⇒ It was thought that the witness had been injured.
Dạng bị động với chủ ngữ thật được viết lại thành It was thought that...
“to have been injured” → quá khứ hoàn thành bị động: had been injured