C# 复制指定节点的所有子孙节点到新建的节点下

XmlElement mask_list = xmlDoc.CreateElement("mask_list");
XmlElement procedure = xmlDoc.CreateElement("procedure");
XmlNode xn_mask_list = xmlDoc.DocumentElement.SelectSingleNode("/xwsp/lab_list/lab[name/text()=‘111‘]/mask_list");
XmlNode xn_procedure = xmlDoc.DocumentElement.SelectSingleNode("/xwsp/lab_list/lab[name/text()=‘111‘]/procedure");
if (xn_mask_list != null)
{
    mask_list.InnerXml = xn_mask_list.InnerXml;
}
if (xn_procedure != null)
{
    procedure.InnerXml = xn_procedure.InnerXml;
}