阅读以下程序 public class Shape { private string comments; protected string name; public string Name{ get{ return name;} set{name = value;}} public void Draw() {} } public class Rectangle:Shape { protected int width; protected int height; public int Width{get{return width;} set{width=value;}} public int Height{get{return height;} set{height=value;}} public int ComputeArea(){} } 以上Shape类中在Rectangle类中不可见的是( )