How much one enjoys himself travelling depends largely on who/whom he goes with,为什么可以是who?

题目

How much one enjoys himself travelling depends largely on who/whom he goes with,为什么可以是who?
不是说宾格用whom吗

答案

whom作宾语无误
定语从句中who既可以作主语又可作宾语,whom就只能作宾语
（How much one enjoys himself travelling） depends largely on （who/whom ）he goes with
此处两个都可