open class Student(var name: String, var age: Int) {
    open fun say() {
        println("name: $name, age: $age, say ------")
    }
}

class G2Student(name: String, age: Int, var email : String) : Student(name, age) {

    override fun say() {
        println("name: $name, age: $age, email: $email,  say ------")
    }
}


fun main() {
    val p =Student("adley", 18)
    p.say()

    val g2p = G2Student("孙晓辉", 20, "Beijing")
    g2p.say()
}