导航栏二级菜单在ie6下不能显示一行

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导航栏二级菜单在ie6下 有两个栏目不能显示一行  图：
ie6下前边的栏目正常：
后两个栏目不能显示一行：
似乎是二级栏目长度不能超过一级栏目马上要用  所以希望大家仔细看下  帮帮忙啦前台代码：
    <td align="left" width="760" >
                 <ul id="nav">
                    <li>
                       <span style="vertical-align:middle"> <img src="image/01sy0000.jpg" width="4" height="14" alt="" /></span></li>
                    <li><a href="index.aspx"><span class="STYLE23">首&nbsp; 页</span></a></li>
                    <li>
                        <span style="vertical-align:middle"><img src="image/01sy0001.jpg" width="4" height="14" alt="" /></span></li>
                    <li><a href="gk.aspx?cid=38"><span class="STYLE23">概&nbsp; 况</span></a>
                        <ul>
                            <li><a href="gk.aspx?cid=38">郑州美术馆</a></li>
                            <li><a href="gk.aspx?cid=37">郑州画院</a></li>
                            <li><a href="gk.aspx?cid=39">升达分馆</a></li>
                        </ul>
                    </li>
                    <li>
                        <span style="vertical-align:middle"><img src="image/01sy0002.jpg" width="4" height="14" alt="" /></span></li>
                    <li><a href="xxzy.aspx"><span class="STYLE23">新&nbsp; 闻</span></a>
                        <ul>
                            <li><a href="articlelist.aspx?id=20">重要文件</a></li>
                            <li><a href="articlelist.aspx?id=21">本馆活动</a></li>
                            <li><a href="articlelist.aspx?id=23">综合信息</a></li>
                        </ul>
                    </li>
                    <li>
                       <span style="vertical-align:middle"> <img src="image/01sy0003.jpg" width="4" height="14"  alt="" /></span></li>
                    <li><a href="chzl.aspx"><span class="STYLE23">策划展览</span></a>
                        <ul>
                            <li><a href="articlelist.aspx?id=26">长期展览</a></li>
                            <li><a href="articlelist.aspx?id=27">展览预告</a></li>
                            <li><a href="articlelist.aspx?id=28">当前展览</a></li>
                            <li><a href="articlelist.aspx?id=29">以往展览</a></li>
                        </ul>
                    </li>
                    <li>
                        <span style="vertical-align:middle"><img src="image/01sy0004.jpg" width="4" height="14" alt="" /></span></li>
                    <li><a href="dcjp1.aspx"><span class="STYLE23">典藏精品</span></a>
                        <ul>
                            <li><a href="Piclist.aspx?id=30">特色馆藏</a></li>
                            <li><a href="Piclist.aspx?id=31">国画</a></li>
                            <li><a href="Piclist.aspx?id=32">油画</a></li>
                            <li><a href="Piclist.aspx?id=33">书法</a></li>
                            <li><a href="Piclist.aspx?id=34">雕塑</a></li>
                            <li><a href="Piclist.aspx?id=35">摄影</a></li>
                            <li><a href="Piclist.aspx?id=36">其他</a></li>
                        </ul>
                    </li>
                    <li>
                        <span style="vertical-align:middle"><img src="image/01sy0005.jpg" width="4" height="14" alt="" /></span></li>
                    <li><a href="xsyj.aspx"><span class="STYLE23">学术研究</span></a>
                        <ul>
                            <li><a href="articlelist.aspx?id=40">出版专著</a></li>
                            <li><a href="articlelist.aspx?id=41">发表论文</a></li>
                            <li><a href="articlelist.aspx?id=42">课题研究</a></li>
                            <li><a href="articlelist.aspx?id=43">馆刊简介</a></li>
                            <li><a href="articlelist.aspx?id=44">图书资料</a></li>
                        </ul>
                    </li>
                    <li>
                       <span style="vertical-align:middle"> <img src="image/01sy0006.jpg" width="4" height="14" alt="" /></span></li>
                    <li><a href="ggwj.aspx"><span class="STYLE23">公共文教</span></a>
                        <ul>
                            <li><a href="articlelist.aspx?id=45">美术常识</a></li>
                            <li><a href="articlelist.aspx?id=46">美术馆之友</a></li>
                            <li><a href="articlelist.aspx?id=47">美术馆志愿者</a></li>
                        </ul>
                    </li>
                    <li>
                        <span style="vertical-align:middle"><img src="image/01sy0007.jpg" width="4" height="14" alt="" /></span></li>
                    <li><a href="lxwm.aspx"><span class="STYLE23">联系我们</span></a></li>
                </ul>
            </td>css代码：
/*导航菜单 */#nav {
height: 24px;
list-style-type:none;
padding-left:10px;
line-height:24px;
overflow:visible;
background:#FFFFFF;
display:inline-table;
width: 695px;
position: static;
margin-left:40px;
 white-space:nowrap;
  z-index: 10;
    }#nav a {
 display:block; width:80px; text-align:center; 
}#nav a:link  {
color:#000000;
text-decoration:none; font-family:微软雅黑;
font-weight: normal;
}
#nav a:visited  {
color:#000000;
text-decoration:none;
}
#nav a:hover  {
color:#FFFFFF;
text-decoration:none;
font-weight:bold;
background-color: #FF9900;
}#nav li ul {
 line-height: 24px;  
 list-style-type: none;
 text-align:left;
 left: -999px; 
 width:auto;
 position: absolute;
 background:#FBB137;
 overflow: visible;
 white-space:nowrap;
 vertical-align:bottom;
  z-index: 10;
}
#nav li {
float: left;
overflow: visible;
text-align: center;
 white-space:nowrap;
  width:auto;
  z-index: 10;
}
#nav li ul li{
float: left;
width:auto;
color:White;   /*float就是子菜单横向的关键,可以继承父菜单而省略float*/
overflow: visible;
 white-space:nowrap;
   z-index: 10;
}
#nav li ul a{
display: block;
width:auto;
padding-left:15px;
color:White;
font-family: "微软雅黑";
font-size: 14px;
font-style: normal;
font-weight: bold;
}#nav li ul a:link  {
color:#FFFFFF;
text-decoration:none;
font-family: "微软雅黑";
font-size: 14px;
font-style: normal;
font-weight: bold;
background-color: #FF9900;
}
#nav li ul a:visited  {
color:#FFFFFF;
text-decoration:none;
background-color:#FF9900;
font-family: "微软雅黑";
font-size: 14px;
font-style: normal;
font-weight: bold;
}
#nav li ul a:hover  {
color:#FFFFFF;
text-decoration:none;
font-weight:bold;
background:#FBB137;
font-family: "微软雅黑";
font-size: 14px;
font-style: normal;
}#nav li:hover ul {
left:auto;
font-family: "微软雅黑";
font-size: 16px;
font-style: normal;
font-weight: bold;
background-color: #FF9900;
}#nav li.sfhover ul {
left:auto;
background-color: #FF9900;
}#content {
 clear: left; 
}