nobody knew who was at fault for this accident.
she is not at fault with this case.
she is not at faultin this case.

위의 세문장에서... 다 같은 내용인 거 같은데 왜 전치사가 다른가요? (굵은 색으로 표시한 것)
어떨 때 for, with, in 을 쓰나요???
너무 헷갈립니다ㅠ