Because of the grammatic difference, there's no usage such as 'whom' in the sentence structure in Chinese. For example, if you translated 'To whom are you referring?' and 'Who is that lady over there?' into Chinese, it would be '你指的是誰？' and '那邊的女士是誰？', Both are '誰' and pronounced the same 'shéi'. I hope this answered your question.