这个Linq查询的C扩展方法等价于什么?

在 this example:

public void Linq40()
{
    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };

    var numberGroups =
        from n in numbers
        group n by n % 5 into g
        select new { Remainder = g.Key, Numbers = g };

    foreach (var g in numberGroups)
    {
        Console.WriteLine("Numbers with a remainder of {0} when divided by 5:",
            g.Remainder);

        foreach (var n in g.Numbers)
        {
            Console.WriteLine(n);
        }
    }
}

什么是纯c#等价物?我明白了。。。

var numberGroups = numbers.GroupBy(n => n % 5)...

但是 into 条款有点神秘,我想不出怎么得到 Key 从 Select .