使用C＃获取XML元素及其子节点的限定名称

Edited:

I'm trying to accomplish three things here: get XmlNode Query, get the XmlNode QueryId and get the value of a:schemaLocation but the after parsing they end up as null. If I remove the qualified name from the XML, the C# bit works fine. How should I re-write my code?I'm trying to accomplish three things