php 取xml值的问题


xml代码如下：
<Section SectionID="3">
  <SectionReadmeTxt>啊啊啊啊啊</SectionReadmeTxt>
  <SectionScore>0</SectionScore>
  <GroupSum>0</GroupSum>
  <QuestionSum>0</QuestionSum>
  <Question>
  <QuestionID>1</QuestionID>
</Section>
<Section SectionID="2">
  <SectionReadmeTxt>啊啊啊啊啊</SectionReadmeTxt>
  <SectionScore>0</SectionScore>
  <GroupSum>0</GroupSum>
  <QuestionSum>0</QuestionSum>
  <Question>
  <QuestionID>1</QuestionID>
</Section>
<Section SectionID="13">
  <SectionReadmeTxt>啊啊啊啊啊</SectionReadmeTxt>
  <SectionScore>0</SectionScore>
  <GroupSum>0</GroupSum>
  <QuestionSum>0</QuestionSum>
  <Question>
  <QuestionID>1</QuestionID>
</Section>php代码如下
<?php
header("Content-type: text/html; charset=utf-8");
$xml = new DOMDocument();
$xml->load('aaa.epp');$id = $xml->getElementsByTagName('Section');
foreach ($id as $id){
$names =$id->getElementsByTagName("SectionID");;
$name3 = $names->item(0)->nodeValue;
echo "name3：".$name3."<br/><br/>";
}
?>
上面的php代码不对，请问如何使用php dom 将<Section SectionID="3">中的SectionID的值取出来，请各位帮帮忙，谢谢了