linq to xml There are multiple root elements.

 添加xml结点的时候

var temp2 = temp1.Element("staticContent");
            if (temp2 != null)
            {
                string str = "<remove fileExtension=".svg" />
               <mimeMap fileExtension=".svg" mimeType="image/svg+xml" />
               <remove fileExtension=".nupkg" />
               <mimeMap fileExtension=".nupkg" mimeType="application/zip, application/octet-stream" />
               <remove fileExtension=".webm" />
               <mimeMap fileExtension=".webm" mimeType="video/webm" />
               <remove fileExtension=".mp4" />
               <mimeMap fileExtension=".mp4" mimeType="video/mp4" />";
                temp2.AddFirst(XElement.Parse(str));
            }

必须把多个节点从，拆分开来，逐个添加

解析xml字符串的时候

    [Test]
        public void XmlTest()
        {
            string xml = "<Record ID="135" Key="CustomTableItemID" /> <Record ID="23" Key="CustomTableID" />";
            XElement element = XElement.Parse(xml);
            Console.WriteLine(element);
        }

需要添加一个根结点，才能进行解析