【醒目】 He has three cousins,three of whom are clever

问题描述:

【醒目】 He has three cousins,three of whom are clever
为什么用whom不能用them

逗号不能连接2个句子.如果用them的话那就是2个句子,不正确.要用them也可以,不过要在逗号前加个连词,如and.用whom表示它不是个独立的句子,而是从句.还清楚吗?