请根据注释将以下程序画横线处补充完整。 ____class Shape {//定义一个抽象类Shape public int width,height; public ____(int width, int height){ this.width=width; ____.height =height; } abstract double getArea(); //求图形面积的抽象方法 } class Square ____ Shape {//从抽象类Shape继承的子类--矩形类 public double ____() { //求图形面积的抽象方法 return width*height; } public Square(int width, int height){ ____(width,height); } } public class TestAbstractClass1{ public static void main(String[] args){ Shape box=new Square(25,25); System.out.println("box Area:"+box.getArea()); } }