為什麼要加,...,?

類型1:(不加,...,)
The woman who lives next door is a doctor.

類型2:(加,...,)
My brother Rob,who lives in Australia,is a doctor.

問題:(為什麼是類型2,而不是類型1,還是我本書印錯)
A friend of mine,whose father is the manager of a comany,helped me to get a job