List<GestInfo> gList=new List<GestInfo>();
var query=from guest in gList
where ((guest.Name.Substring(0,1)=="徐"||guest.Name.Length==2)&&guest.Age>=19)
select guest;
http://msdn.microsoft.com/zh-cn/library/bb310804.aspx
原文：http://www.cnblogs.com/hellenycl/p/3665171.html