what happened to him
彼がどうなったか知らない。
I don't know what happened to him.
彼がどうなったか教えて下さい。
Please tell me what happened to him.
彼がどうなったか誰も想像できない。
No one can imagine what happened to him.
私は彼がどうなったかしらない。
I don't know what became of him.
だれも、彼がどうなったか知らない。
No one knows what happened to him.