一道英语试题请求详解I have many friends ,-------some are businessmen .

思路：
不能确定是不是定语从句的话要看下答案,从答案中我们可以知道是“他们中的一些”,从而判定为定语从句.先行词为“friends”,属“人物”,因此可以用who,whom,which.在确定用哪个之前,要先了解从句（后半句）如果单独成句的话,它的结构是怎么样的.可以确定为Some of my friends are businessmen,也可为(Out) Of all my firneds,some are businessmen.英语句型灵活,你要多读~OK,确定之后,可以判断为D了,用whom,of是介词,后面接宾格.
你还可能对A有疑惑,解释一下,如果A的话,句型应该为I have many friends, and some of them are businessmen.或I have many friends, and of them,some are businessmen.注意"and",两个分句之间要有连接词.