c# 可变性解析（协变和逆变）

class Program
    {
       static void Main(string[] args)
       {
            Course c = new ConsoleApplication2.Course();
            Project p = new Project();
            p.Name = "Course 类的属性";
            GetProject(c);
            Console.ReadKey();
        }
        public static void GetProject(Project course) {
            Console.WriteLine(course.Name);
        }
    }
    public class Project{
        public string Name { get; set; }
        public string Age { get; set; }
    }
    public class Course :Project{
        public string Address { get; set; }
    }