二、請回答下列問題：(一)請詳細說明物件導向程式設計(Object-Oriented Programming)三個特性。(5 分)

1. A couple has the same chance to give birth to a boy and a girl, and decides to have 3 children. If none of the 3 is a girl, they will try again; and if they still don't get a girl, they will try once more. If the random variable \( X \) denotes the number of children the couple will have following this scheme, then what is the expected value of \( X \)? (1)