查询C#中另一个列表中的列表

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

class Program
{
    static void Main(string[] args)
    {
        List<List<int>> lists = new List<List<int>>
        {
            new List<int> { 1, 2, 3 },
            new List<int> { 4, 5, 6 },
            new List<int> { 7, 8, 9 }
        };

        var query = from list in lists
                    from item in list
                    where item > 4
                    select item;

        foreach (var item in query)
        {
            Console.WriteLine(item);
        }
    }
}