.Net 操作XML，快速查找节点

XML:
<EHR>
... 
           <item name='张三' date='2011-11-12'  />
            <item name='李四' date='2009-10-12'  />
            <item name='肖建' date='1982-11-02'  />
...
</EHR>
            XmlNode sxn = xmlDoc.SelectSingleNode("//EHR/item[@name='张三' and @data='2011-12-12']");