public static void ConvertStudentName(string name)
 {
     // you can not use an instance member Age
     var student = new Student();
     if (student.Age>0)
     {
     }
 }
        //The method some times is like a contract, What you pass in and what ir returns
        public List<Student> GetStudents()
        {
            List<Student> list1 = new List<Student>();
            Student student1 = new Student();
            list1.Add(student1);
            Student student2 = new Student();
            list1.Add(student2);

            return list1;
        }
        static void TestStudent()
        {
            // here is an example of calling static
            Student.ConvertStudentName("myname");

            Student studentTest = new Student();

            Student studentTest2 = new Student(19);

            studentTest.Age = -10;
            Console.WriteLine(studentTest.Age);

            studentTest.LastName = "Gao";
            Console.WriteLine(studentTest.LastName);

            Console.ReadLine();
        }