List<Grade> lst = new List<Grade>();

        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                Student student = new Student();
                student.Id = 1;
                student.GradeId = 1;
                student.Score = 100;

                Student stu = new Student();
                stu.Id = 2;
                stu.GradeId = 2;
                stu.Score = 10;

                Grade grade = new Grade();
                grade.Id = 1;
                grade.Students = student;

                Grade g = new Grade();
                g.Id = 2;
                g.Students = stu;

                lst.Add(grade);
                lst.Add(g);

 　　　　    TreeNode rootNode = new TreeNode("分数");
                TreeView1.Nodes.Add(rootNode);
            }
        }

上面的是一个集合中对象是班级，班级中包含学生。

现在要把他绑定到treeview中，用递归，分数下是“班级ID”，班级下是“学生Score”，请问用递归怎么弄？希望有实例。望不吝赐教，不胜感激。