Do you know the name of the company 【in which】 she 【works
=Do you know the name of the company 【where】 she 【works】
【先行词在从句中做状语,表示地点】
=Do you know the name of the company (which/that)she 【works in】?
【先行词在从句中做介词in的宾语】
关键:看清楚先行词与定语从句中谓语动词的关系:是动词与宾语的关系,用关系代词;是动词和状语的关系,用关系副词(或介词加关系代词结构).