He is the only one of my friends who is working hand1. He is one of my friends who are working hard.2. He is the only one of my friends who is working hard.这两句话who的先行词是什么 请解释 谢谢

问题描述:

He is the only one of my friends who is working hand
1. He is one of my friends who are working hard.
2. He is the only one of my friends who is working hard.
这两句话who的先行词是什么 请解释 谢谢