XML删除未含有条件的子节点

<power_line>
<name>嘉华305线 </name>
<sap_id>5020-S-0000-0065 </sap_id>
        <dydj>35kV </dydj>
<poles>
<pole>
<name>嘉华305线电缆电缆#0 </name>
<xh>0 </xh>
<sap_id>000000000040719166 </sap_id>
</pole>
<pole>
<name>嘉华305线电缆支架 </name>
<xh>0 </xh>
<sap_id>000000000040627384 </sap_id>
<jd>120.7071280158 </jd>
<wd>30.6240158394 </wd>
</pole>
<pole>
<name>嘉华305线电缆电缆#1 </name>
<xh>1 </xh>
<sap_id>000000000040716119 </sap_id>
</pole>
        </poles>
</power_line>


我想把不含有 <jd>的子节点都删除掉.请问要怎么做?

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遍历 pole + 判断 删除...

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或者：
C# code:
using System;
using System.Diagnostics;
using System.Xml;

namespace ConsoleApplication9 {
class Program {
static void Main() {
string xml = @"
<power_line>
<name>嘉华305线 </name>
<sap_id>50