who和whom在定语从句中都指人，只是who是做主语，而whom是做宾语的。 比如： Do you know whom he is look for? whom就是look for的宾语 John's elder brother who's a doctor has married. who代替elder brother作定语从句的主语。 祝愿学业进步！
who 可以用来做主语和宾语 可用于非限定性定语从句 whom 只能做宾语或介词宾语 做宾语时不能用于非限定性定语从句 I do not know the person with whom you are talking. i do not know the person who/whom you are talking with. 希望对你有帮助