如何在c中读取xml

无法在c#中读取此xml。如何从这个xml 中获取货币和汇率

我用了这个代码

XmlTextReader xmlTextReader = new XmlTextReader(new StringReader(xmlfile));
XmlDocument doc = new XmlDocument();
XmlNode node = doc.ReadNode(xmlTextReader);

但是没有得到值。

 <?xml version="1.0" encoding="UTF-8"?>
 <gesmes:Envelope xmlns:gesmes="http://www.gesmes.org/xml/2002-08-01" xmlns="http://www.ecb.int/vocabulary/2002-08-01/eurofxref">
<gesmes:subject>Reference rates</gesmes:subject>
<gesmes:Sender>
    <gesmes:name>European Central Bank</gesmes:name>
</gesmes:Sender>
<Cube>
    <Cube time='2013-02-14'>
        <Cube currency='USD' rate='1.3327'/>
        <Cube currency='JPY' rate='124.39'/>
        <Cube currency='BGN' rate='1.9558'/>
        <Cube currency='CZK' rate='25.383'/>
        <Cube currency='DKK' rate='7.4604'/>
        <Cube currency='GBP' rate='0.85940'/>
        <Cube currency='HUF' rate='292.52'/>
        <Cube currency='LTL' rate='3.4528'/>
        <Cube currency='LVL' rate='0.6997'/>
        <Cube currency='PLN' rate='4.1765'/>
        <Cube currency='RON' rate='4.3871'/>
        <Cube currency='SEK' rate='8.4492'/>
        <Cube currency='CHF' rate='1.2293'/>
        <Cube currency='NOK' rate='7.3605'/>
        <Cube currency='HRK' rate='7.5863'/>
        <Cube currency='RUB' rate='40.1712'/>
        <Cube currency='TRY' rate='2.3605'/>
        <Cube currency='AUD' rate='1.2879'/>
        <Cube currency='BRL' rate='2.6220'/>
        <Cube currency='CAD' rate='1.3343'/>
        <Cube currency='CNY' rate='8.3062'/>
        <Cube currency='HKD' rate='10.3352'/>
        <Cube currency='IDR' rate='12873.40'/>
        <Cube currency='ILS' rate='4.9036'/>
        <Cube currency='INR' rate='71.8730'/>
        <Cube currency='KRW' rate='1445.93'/>
        <Cube currency='MXN' rate='16.9523'/>
        <Cube currency='MYR' rate='4.1170'/>
        <Cube currency='NZD' rate='1.5715'/>
        <Cube currency='PHP' rate='54.251'/>
        <Cube currency='SGD' rate='1.6491'/>
        <Cube currency='THB' rate='39.728'/>
        <Cube currency='ZAR' rate='11.8588'/>
    </Cube>
</Cube>

XDocument doc = XDocument.Load(url);
XNamespace gesmes = "http://www.gesmes.org/xml/2002-08-01";
XNamespace ns = "http://www.ecb.int/vocabulary/2002-08-01/eurofxref";
var cubes = doc.Descendants(ns + "Cube")
               .Where(x => x.Attribute("currency") != null)
               .Select(x => new { Currency = (string) x.Attribute("currency"),
                                  Rate = (decimal) x.Attribute("rate") });
foreach (var result in cubes)
{
    Console.WriteLine("{0}: {1}", result.Currency, result.Rate);
}

string query = "//Cube[@currency and @rate]";//select the cube node that has "currency" and "rate" attributes.
XmlNodeList nodes = doc.SelectNodes(query);
foreach (XmlNode node in nodes)
{
    string currency = node.Attributes["currency"].Value;
    string rate = node.Attributes["rate"].Value;
    Console.WriteLine("currency: {0}, rate: {1}", currency, rate);
}