最好是给他们取ID,不过不取也行:
<b>123</b>
<b>456</b>
<ul>
<li>789
</ul>
<script language="JavaScript">
<!--
alert(document.getElementsByTagName('B')[0].innerHTML);
alert(document.getElementsByTagName('B')[1].innerHTML);
alert(document.getElementsByTagName('LI')[0].innerHTML);
//-->
</script>
<b>123</b>
<b>456</b>
<ul>
<li>789
</ul>
<script language="JavaScript">
<!--
alert(document.getElementsByTagName('B')[0].innerHTML);
alert(document.getElementsByTagName('B')[1].innerHTML);
alert(document.getElementsByTagName('LI')[0].innerHTML);
//-->
</script>
<b id=aaa>123</b>
<b id=bbb>456</b>
<ul>
<li id=ccc>789
</ul>
<script>
alert(document.aaa.innerText+"\n"+document.bbb.innerText+"\n"+document.ccc.innerText);
</script>