The man who lives in that house is my uncle --------是限制性定语从句,因为还存在the man in this house,或者the man next door,或者the man who is staying with us .一般说,who / which前面没有逗号时,就是限制性定语从句.
Uncle Wang,who lives across the street,is a friend of my parents' .--------这是非 限制性定语从句,因为who前面有个逗号,并且不涉及 Uncle Chen或者Uncle Li.