.fenlei1{
????padding:0;
????margin:0;
???}
???.li1{
????float:left;
????height:30px;
????line-height:30px;
???}
???.fenlei1 li{
????height:40px;
????line-height:40px;
????z-index:3;
????background-image:url(../images/1.png);
????background-repeat:no-repeat;
????background-position:right;
????padding:0;
????margin:0;
???}
???.fenlei1 li a{
????color:#313131;
????padding-left:15px;
???}
???.fenlei1 li a:hover{
????text-decoration:underline;
????font-weight:bold;
????color:#e4393c;
????
???}
???.fenlei1 li:hover{
????border:1px solid #DDD;
????border-right:0;
????box-shadow: 0 0 8px #DDD;
????background-image:none;
???}
???.subfenlei{
????display:none;
????width:715px;
????position:absolute;
????top:0px;
????left:180px;
????border:1px solid #DDD;
????z-index:4;
????background:white;
????box-shadow: 0 0 8px #DDD;
????padding-left:0px;
???}
???.leftsub{
????background:white;
????float:left;
????width:490px;
????margin:5px;
???}
???.rightsub{
????background:white;
????float:left;
????width:200px;
????margin:5px;
???}
???.fenlei1 li:hover ~.subfenlei{
????display:block;
???}
???
???.fenlei1 li:hover ~span{
????background:white;
????display:inline-block;
????z-index:20;
????width:20px;
????height:40px;
????float:right;
????position:absolute;
????top:1px;
????left:175px;
???}
???.leftsub dl{
????display:block;
????border-bottom:1px solid #EEE;
????padding-botting:6px;
????overflow:hidden;
???}
???.leftsbu dl dt{
????display:block;
????float:left;
????width:60px;
????text-align:right;
????height:22px
????line-height:22px;
???}

<div class="fenlei">
????<ul class="fenlei1">
?????<li><a href="#">信息科學(xué)與工程學(xué)院</a></li><span></span>
??????<div class="subfenlei">
????????<div class="leftsub">
?????????<dl>
??????????<dt><a href="#">專業(yè)</a></dt>
??????????<dd>
??????????<a href="#">計算機科學(xué)與技術(shù)</a><a href="#">光電子</a><a href="#">信息安全</a>
??????????</dd>
?????????</dl>???????????????
????????</div>
????????<div class="rightsub">

代碼貼出來啊