java – 封闭类型的静态嵌套子类仍然可以引用私有字段成员,为什

public class A
{
    private int privateVar = 1;
    protected int protectedVar = 2;

    static class B extends A
    {
        public int getPrivateVariable()
        {
            return privateVar; //error: Cannot make a static reference to the non-static field memberVariable
        }

        public int getProtectedVariable()
        {
            return protectedVar; //OK: Why?
        }

        public int getPrivateUnfair()
        {
            return super.privateVar; //Why this can be accessed using super which the protected member doesn't require.
        }
    }
}

>为什么静态嵌套类可以自由访问实例成员？
>为什么保护和私有变量的访问方式有所不同？但是,如果嵌套类是非静态内部类,那么情况并非如此？

编辑：

>为什么关键字super允许访问封闭类型的私有成员？