ASP.NET Entity Framework可以使用Include方法来加载嵌套的相关数据。以下是一个示例代码：

using System;
using System.Linq;
using Microsoft.EntityFrameworkCore;

namespace EFIncludeExample
{
    public class Student
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public int GradeId { get; set; }
        public Grade Grade { get; set; }
    }

    public class Grade
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public int SchoolId { get; set; }
        public School School { get; set; }
    }

    public class School
    {
        public int Id { get; set; }
        public string Name { get; set; }
    }

    public class SchoolContext : DbContext
    {
        public DbSet Students { get; set; }
        public DbSet Grades { get; set; }
        public DbSet Schools { get; set; }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            optionsBuilder.UseSqlServer("your_connection_string");
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            using (var context = new SchoolContext())
            {
                var students = context.Students
                    .Include(s => s.Grade) // 加载嵌套的Grade数据
                    .ThenInclude(g => g.School) // 加载嵌套的School数据
                    .ToList();

                foreach (var student in students)
                {
                    Console.WriteLine($"Student: {student.Name}, Grade: {student.Grade.Name}, School: {student.Grade.School.Name}");
                }
            }
        }
    }
}

在上面的示例代码中，我们有三个实体类：Student、Grade和School。Student类拥有一个Grade属性，Grade类拥有一个School属性。我们使用Include方法来加载嵌套的Grade和School数据。在Main方法中，我们创建了一个SchoolContext实例，并使用Include和ThenInclude方法加载嵌套的数据。然后，我们遍历所有学生，并打印出学生的姓名、年级和学校。