Person p = new Person();
            p.Id = 1;
            p.Age = 23;
            p.Name = "张飞";
            object o = p;
            Person p1 = o as Person;
            Console.WriteLine(p1.Name);         //输出    张飞  能够将o强制转换Person类型


            Person p1 = new Person(1, 20, "张飞");
            Person p2 = new Person(2, 21, "关羽");
            Person p3 = new Person(3, 22, "刘备");
            List<Person> PersonList = new List<Person>();
            PersonList.Add(p1);
            PersonList.Add(p2);
            PersonList.Add(p3);
            object o = PersonList;
            List<Person> PersonList1 = o as List<Person>;
            Console.WriteLine(PersonList1[1].Name); //输出    关羽  讲o强制转换List强类型集合


            Person p4 = new Person(4, 24, "赵云");
            object o = p4;
            Console.WriteLine(p4 is Person);    //输出    True

            List<Person> PersonList = new List<Person>();
            object o1 = PersonList;
            Console.WriteLine(o1 is Person);    //输出    False
            Console.WriteLine(o1 is List<Person>);  //输出    True