Package, Interface and Abstract Class

package pck1;
 public class A
 {
  int x = 10;
  public int y = 20; 
 }

package pck2;
 import pck1.*;
 class Test
 {
  public static void main(String []args)
  {
    A a = new A();	         // line 7
    System.out.println(a.x);	 // line 8
    System.out.println(a.y);	 // line 9
  }
}

abstract class A 
{
  int a = 100;
  public abstract void showA(); }

public class B extends A
{
  _ _ _ _ _ _ _ _ _         // Fill the blank

  public static void main(String []args)
  { 
    A objA = new B();
    objA.showA(); 
  }
}

public interface A { public void showA(); }  

// Class declarations :
interface A {}
class B {}
class C extends B implements A {}
class D implements A {}
 
// Declaration statements :
B b = new B();
C c = new C();
D d = new D();