C# 从两个列表中计算所有可能的项目对？

我有两个阵列：

string[] Group = { "A", null, "B", null, "C", null };

string[] combination = { "C#", "Java", null, "C++", null }; 

我希望返回所有可能的组合，如：

{ {"A","C#"} , {"A","Java"} , {"A","C++"},{"B","C#"},............ }

应忽略空值

Group.Where(x => x != null)
     .SelectMany(g => combination.Where(c => c != null)
                                 .Select(c => new {Group = g, Combination = c})
     );

或者：

from g in Group where g != null
from c in combination where c != null
select new { Group = g, Combination = c }

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谢谢Mehrdad的及时回复。你知道如何有效地进行排列而不仅仅是组合吗？（意思是{“A”、“C”}和{“C”}，“A”}将被视为两个独立的项目）？