请问xpath怎么写

请教xpath如何写

XML code

<class>  <student>    <no>1</no>    <name>Ann</name>    <sex>female</sex>    <age>15</age>    <score>90</score>  </student>  <student>    <no>2</no>    <name>Bob</name>    <sex>male</sex>    <age>16</age>    <score>80</score>  </student>  <student>    ……  </student>  <student>    ……  </student></class>

C# code

        string strXml = @"<class>  <student>    <no>1</no>    <name>Ann</name>    <sex>female</sex>    <age>15</age>    <score>90</score>  </student>  <student>    <no>2</no>    <name>Bob</name>    <sex>male</sex>    <age>16</age>    <score>80</score>  </student>  <student>    <no>3</no>    <name>ttt</name>    <sex>j</sex>    <age>15</age>    <score>92</score>  </student>  <student>     </student></class>";        XmlDocument xdoc = new XmlDocument();        xdoc.LoadXml(strXml);        string strXPath = string.Empty;        strXPath = "/class/student[score>=90]";        XmlNodeList oXmlNodes = xdoc.SelectNodes(strXPath);        foreach (XmlNode node in oXmlNodes)        {            string strName = node.SelectSingleNode("/class/student/name").InnerText ;        }
[解决办法]
应该是不可以的。就像冰箱里有N多瓶饮料，你能否不开冰箱就喝到其中的一瓶呢。