大家帮我看看,为什么这个列表可以横排?
代码如下:   
  <!DOCTYPE   html   PUBLIC    "-//W3C//DTD   XHTML   1.0   Transitional//EN "    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd ">  
  <html   xmlns= "http://www.w3.org/1999/xhtml "   lang= "GBK ">  
 	 <head>  
 		 <meta   http-equiv= "Content-Type "   content= "text/html;   charset=GBK "   />    
 		 <title> Insert   title   here </title>  
 		   		 <style   type= "text/css ">   		  		 
 		#submenu   {   MARGIN:   0px   8px   0px   8px;   PADDING:   4px   0px   0px   0px;   BORDER:   #fff   1px   solid;   BACKGROUND:   #dfdfdf;   COLOR:   #666;   HEIGHT:25px;   }  		  		 
 		#submenu   ul   {   CLEAR:   left;   MARGIN:   0px;   PADDING:0px;   BORDER:   0px;   LIST-STYLE-TYPE:   none;   TEXT-ALIGN:   center;   DISPLAY:inline;   }   #submenu   li   {   FLOAT:   left;   DISPLAY:   block;   MARGIN:   0px;   PADDING:   0px;   TEXT-ALIGN:   center}  		 
 		#submenu   li   a   {   DISPLAY:   block;   PADDING:2px   3px   2px   3px;   BACKGROUND:   url(images/icon_dot_lmenu.gif)   transparent   no-repeat   2px   8px;   FONT-WEIGHT:   bold;   WIDTH:   100%;   COLOR:   #444;   TEXT-DECORATION:   none;   }   #submenu   li   a:hover   {   BACKGROUND:   url(images/icon_dot_lmenu2.gif)   #C61C18   no-repeat   2px   8px;   COLOR:   #fff;   }  		 
 		#submenu   ul   li#one   A   {   WIDTH:   60px}   #submenu   ul   li#two   A   {   WIDTH:   80px}   #submenu   ul   li#three   A   {   WIDTH:   80px}   #submenu   ul   li#four   A   {   WIDTH:   90px}   #submenu   ul   li#five   A   {   WIDTH:   80px}   #submenu   ul   li#six   A   {   WIDTH:   80px}   #submenu   ul   li#seven   A   {   WIDTH:   60px}   #submenu   ul   li#eight   A   {   WIDTH:   90px}   #submenu   ul   li#nine   A   {   WIDTH:   80px} 
 		 </style>    
 	 </head>  
 	 <body>  
 		 <div   id= "header ">  </div>  
 		 <div   id= "mainbox ">  
 			 <div   id= "menu ">    
 				 <div   id= "submenu ">  
 					 <ul>  
 						 <li   id= "one ">  
 							 <a   title= "首页 "   href= "http://www.w3cn.org/ "> Home </a>  
 						 </li>  
 						 <li   id= "two ">  
 							 <a   title= "关于我们 "   href= "http://www.w3cn.org/aboutus.html "> 关于我们 </a>  
 						 </li>  
 						 <li   id= "three ">  
 							 <a   title= "网站标准 "   href= "http://www.w3cn.org/webstandards.html "> 网站标准 </a>  
 						 </li>  
 						 <li   id= "four ">  
 							 <a   title= "标准的好处 "   href= "http://www.w3cn.org/benefits.html "> 标准的好处 </a>  
 						 </li>