jQuery实现二级下拉菜单：
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<title>jQuery二级菜单</title>
<style type="text/css">
body{ font:12px/1.5 "\5FAE\8F6F\96C5\9ED1","\5B8B\4F53",Arial; }
ul,li{ margin:0; padding:0; list-style:none; }
/* m-nav */
.m-nav{ background-color:#06c; width:1000px; height:40px; line-height:40px; margin:0 auto; }
.m-nav li.itm{ display:inline; float:left; width:125px; position:relative; text-align:center; }
.m-nav a.itm-a{ display:block; }
.m-nav a.itm-a:hover{ background-color:#05b; }
.m-nav ul.son{ background-color:#06c; width:125px; position:absolute; left:0; top:40px; display:none; }
.m-nav a.son-itm-a{ display:block; font-size:12px; }
.m-nav a.son-itm-a:hover{ background-color:#05b; }
.m-nav a{ color:#fff; font-size:13px; text-decoration:none; }
</style>
<script type="text/javascript" src="/jquery-latest.min.js"></script>
<script type="text/javascript">
$(document).ready(function(){
$('li.itm').mousemove(function(){
$(this).find('ul').slideDown();
});
$('li.itm').mouseleave(function(){
$(this).find('ul').stop(1,1).slideUp();
});
});
</script>
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