A ture friend is someone with whom we can share our life .其中的"with whom "做什么成分呢?!
A ture friend 主语
is someone 系表结构,做复合谓语
with whom we can share our life .定语从句
A ture friend is someone with whom we can share our life.=A ture friend is someone whom we can share our life with.=A ture friend is someone.we can share our life with him.with 引导的从句不是宾语从句吗？with 是介词，不能引导的宾语从句。whom是关系代词，引导定语从句，whom在定语从句中做介词with的宾语，因为whom做介词with的宾语，此句把介词with放在了关系代词whom的前面。