如何从main中访问嵌套类中的方法

这是我的第一个问题的编辑:所以我又检查了一遍作业。所有的代码都像我的教授想要的那样工作，但只有我之前问的问题是我的问题。-我怎么能执行ShowGrade方法直接从列表(当然)像:list[1].ShowGrade(0)不使用list[1]. s.w ShowGrade(0) ??我把所有的代码都写在这里。Main中的两条控制台线是他想要的(以及他想要的方式)，我对任务的限制是:1. 嵌套类学生类课程(一个学生一个课程)。2. 没有构造函数，只有默认构造函数。3.ShowGrade方法将不在Course类中。4. 没有操作员。(点)在ShowGrade，只有[]5. 方法Q1中只有一个查询。

所以我的代码是:

课程。cs:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace HW_1
{
    public class Course 
    {
        private delegate int Del(Course c);
        internal string courseName { get; set; }
        public  class Student
        {
            internal string stuName { get; set; }
            internal List<int> gradesList { get; set; }
            //internal int ShowGrade(int index)
            //{
            //    return gradesList[index];
            //}
        }
        internal Student s = new Student();
        public override string ToString()
        {
            string gr = null;
            foreach (var g in s.gradesList)
                gr += g + " ";
            return string.Format("{0, -6} {1, -14} {2, -10}", courseName, s.stuName, gr);
        }
    }
}

Program.cs:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace HW_1
{
    class Program
    {
        private delegate bool Del(Course c);
        static void Main(string[] args)
        {
            List<Course> list = new List<Course>
            { 
                new Course {courseName = "C#", s = new Course.Student {stuName = "Jojo", gradesList = new List<int>(){10, 20, 100}}},
                new Course {courseName = "C", s = new Course.Student {stuName = "Bambi", gradesList = new List<int>(){99}}},
                new Course {courseName = "Java", s = new Course.Student {stuName = "Bambi", gradesList = new List<int>(){}}}
            };
            Console.WriteLine("List of courses:");
            Print(list);
            Console.WriteLine("");
            Console.WriteLine("");
            Console.WriteLine("Press P / p for students who passed in average 60 and those who didn't.");
            Console.WriteLine("");
            Console.WriteLine("Press # for C# courses and others.");
            Console.WriteLine("");
            Console.WriteLine("Press any other key for courses with student who have at least one grade of 100 and all oter courses.");
            char ch = (char)Console.Read();
            Del d = ((ch == 'P' || ch == 'p') ? (Del)(c => c.s.gradesList.Count > 0 && c.s.gradesList.Average() >= 60) : ((ch == '#') ? (Del)(c => c.courseName == "C#") : (Del)(c => c.s.gradesList.Contains(100))));
            var x = Q1 <IGrouping<bool, Course>>(list, d);
            Print(x);
            Console.WriteLine("");
            //Console.WriteLine(list[1].ShowGrade(0));
            //Console.WriteLine(list[2].ShowGrade(3));
        }
        static IEnumerable<T> Q1<T>(IEnumerable<Course> list, Del d)
        {
            var query =
                from c in list
                orderby d(c)
                group c by d(c) into g
                select g;
            return (IEnumerable<T>)query;
        }
        static void Print(IEnumerable<IGrouping<bool, Course>> list)
        {
            Console.WriteLine();
            Console.WriteLine();
            Console.WriteLine("Q1 Results:");
            foreach (var g in list)
            {
                Console.WriteLine();
                Console.WriteLine(g.Key);
                Console.WriteLine("---------------");
                foreach (var c in g)
                    Console.WriteLine(c);
            }
        }
        static void Print<T>(IEnumerable<T> list)
        {
            foreach (var l in list)
                Console.WriteLine(l);
        }

    }
}

两个控制台的输出。Writeline必须是:

list[1].ShowGrade(0)
99
list[2].ShowGrade(3)