如何在C #中为现有列表创建include？

using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main()
    {
        // 创建一个现有列表
        List<string> existingList = new List<string> { "A", "B", "C" };

        // 创建一个需要包含的元素列表
        List<string> includeList = new List<string> { "B", "D", "E" };

        // 使用Join操作符将现有列表和包含的元素列表关联起来
        var result = from existing in existingList
                     join include in includeList on existing equals include into temp
                     from t in temp.DefaultIfEmpty()
                     select new { Existing = existing, Include = t };

        // 输出结果
        foreach (var item in result)
        {
            Console.WriteLine("Existing: " + item.Existing + ", Include: " + item.Include);
        }
    }
}