定语从句中whose ,who,whom,that 的区别

whose “谁的”表示从属关系.先行词可以是物,也可以是人.当指代物时可与of which 互换,eg ：Please pass me the book whose cover（of which the cover / the cover of which) is red.
who 表示先行词是人且在从句中作主语(或宾语).
whom 先行词是人且在从句中作宾语.
that 既可指人,也可指物.作宾语或主语.