public class X4_1_3 {

private float a;

public static void m ( ){ }

}

如何使成员变量a被方法m( )访问(　　)

public class X5_2 extends X{

int ab(){

static int aa=10;

aa++;

System.out.println(　　);

}

public static void main(String[] args) {

X5_2 x=new X5_2();

x.ab();

}

}

class Base {

   public void method(){

       System.out.print ("Base method.");

   }

}

class Child extends Base{    

   public void methodB(){

       System.out.print ("Child methodB.");

   }

}

class Sample {

   public static void main(String[] args) {

       Base base= new Child();

       base.methodB();

   }

}