考虑到语言环境，LINQ查询中的空值是否可以回退?

I'm creating a C# .NET 3.5 website. In this website some content is read from an XML file. This XML file is saved from an Excel file, so basically the Excel is a kind of content management system (I cannot use a database in this situation). I am using LINQ to XML to get collections of the content objects so I can work with them on the webforms. I am a just starting with LINQ, but I know the basics like grouping and ordering.I'm creating a C# .NET 3.5 website. In this web