如何通过HtmlAgilityPack获取不太规则的HTML里面的内容

[dzwebs]

我有如下的HTML代码片段

<table border="1" width="99%"> <tr> <td class="FieldLabel" width="20%">录取学校名称<font color="red">*</font></td> <td class="FieldInput" width="30%"> <input type="text" id="xxmcS" readonly="readonly" onclick="showXxWin()" style="width:80%"/> <img id="showXxImg" onclick="showXxWin()" src=/skins/images/default/toolbar/query.png style="POSITION:relative;CURSOR:hand;TOP:5px;LEFT:-25px" width="18" height="18"/> <input type="hidden" id="xxbzmS"/> <input type="hidden" id="xxbxlxdm"/> </td> <td class="FieldLabel" width="15%">录取教育阶段<font color="red">*</font></td> <td class="FieldInput"><select id="jyjd""> <option dataset="jyjdDataset"/> </select>   </td> </tr> <tr> <td class="FieldLabel">招生来源<font color="red">*</font> </td> <td class="FieldInput"> <select id="zsly"> <option dataset="zslyDs"/> </select>  <td class="FieldLabel"></td> <td class="FieldInput"></td> </tr> </table> </fieldset> </form>'},{border:false,bodyStyle:'padding-bottom:10px;padding-top:12px;',height:'100%',html:'<form dataset="zsjgDs" class="L5form"> <fieldset> <legend>学生信息</legend> <table border="1" width="100%"> <tr> <td class="FieldLabel" style="width:20%">学籍号<font color="red">*</font></td> <td class="FieldInput" style="width:30%"> <input type="text" id="grbsm" field="grbsm" maxlength="19" class="TextEditor" style="width:55%"/>      <button onclick="grbsmChange()" id="qButton">查询</button> </td> <td class="FieldLabel" style="width:15%">学生姓名</td> <td class="FieldInput" ><label field="xm"/></td> </tr> <tr> <td class="FieldLabel">毕业学校标识码</td> <td class="FieldInput"><label field="byxxbsm"/></td> <td class="FieldLabel">毕业学校名称</td> <td class="FieldInput"><label field="byxxmc"/></td> </tr> <tr> <td class="FieldLabel">招生年度</td> <td class="FieldInput"><label field="zsnd"/></td> <td class="FieldLabel"></td> <td class="FieldInput"></td> </tr> <tr> <td class="FieldLabel">录取学校标识码</td> <td class="FieldInput"><label field="lqxxbsm"/></td> <td class="FieldLabel">录取学校名称</td> <td class="FieldInput"><label field="lqxxmc"/></td> </tr> </table>

现在，我想通过HtmlAgilityPack获取的是<label field="byxxbsm"/>这个标签里面的内容，怎么获取啊

[Hello World,]

这个标签里没内容，获取标签可用以下方法：

[键盘敲出字]

HtmlDocument doc;
//此处省略将html加载到doc
HtmlNode node = doc.DocumentNode;
HtmlNode byxxbsm = node.SelectSingleNode("//label[@field='byxxbsm']");