On his way home, he met/ ran into an old friend whom he hadn’t seen for 10 years.
考点：on one's way home：在某人回家的路上，这里的home是副词，“回/到家”的意思，地点副词前省略介词(to) ；run into：意外碰到
句子结构：whom引导名词性从句，修饰an old friend。
