many of后什么时候加whom什么时候加them

注意定语从句和并列句的区别.
定语从句是一个主句加上一个从句.
而并列句是两个同等地位的分句,一般需要用分号或者并列词隔开.
明白这点以后,看下这两个句子：
I have a lot of friends,some of whom are foreigners.(正确)
和
I have a lot of friends,some of them are foreigners.（错误）因为这两个半句都是独立的句子,而独立的句子在英语书面语中不用逗号连接.
这句话的正确表达方式有：
I have a lot of friends；some of them are foreigners.注意中间是分号.或者.
I have a lot of friends,and some of them are foreigners.注意中间用and连接.
比较详细了.