高分求助一个简单的问题

<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>首页大焦点图-PConline</title>
<style type="text/css">
<!--@charset "gb2312";
table,td,select,input,div {font-size:12px;}
body { font-size:12px; padding:0; margin:0; height:auto;}
a img {border:0;}
form,input,select,ul,li{margin:0;padding:0;}-->
</style></head>
<body>
<style type="text/css">
/* 数字按钮框样式 */
#imgTitle {FILTER:ALPHA(opacity=70);position:relative;left:0px;text-align:left;overflow: hidden;}
#imgTitle_up {left:0px;text-align: left; height:1px; width:inherit; }
#imgTitle_down {left:0px;text-align: right; width:inherit; }
/* 图片框样式 */
.imgClass {border: 0px solid #000;}
/* 图片文字框样式 */
#txtFrom {text-align: center;vertical-align: middle;}
/* 数字按钮样式 */
.button {text-decoration: none;padding: 2px 7px;background: #7B7B63;margin: 0px;font: bold 9px sans-serif; border-left:#fff 1px solid;}
a.button, a.button:link, a.button:visited {font-family: sans-serif;text-decoration: none;color:#FFFFFF;background-color: #000000;}
a.button:hover {font-family: sans-serif;text-decoration: none;color:#fff;background:#fff; }
.buttonDiv {background: #000000;height: 1px;width: 21px;float: left;text-align: center; vertical-align: middle;}
/*渐变*/ 
.trans { width:90px; background-color:#000;filter : progid:DXImageTransform.Microsoft.Alpha(startX=0, startY=0, finishX=100, finishY=100,style=1,opacity=0,finishOpacity=40);}
</style>
<script language="javascript" type="text/javascript">
var imgWidth=365;              //图片宽
var imgHeight=120;             //图片高
var textFromHeight=0;         //焦点字框高度 (单位为px)
var textStyle="f12";           //焦点字class style (不是连接class)
var textLinkStyle="p1"; //焦点字连接class style
var buttonLineOn="#f60";           //button下划线on的颜色
var buttonLineOff="#000";          //button下划线off的颜色
var TimeOut=5000;              //每张图切换时间 (单位毫秒);
var imgUrl=new Array(); 
var imgLink=new Array();
var imgtext=new Array();
var imgAlt=new Array();
var adNum=0;
//焦点字框高度样式表 开始
document.write('<style type="text/css">');
document.write('#focuseFrom{width:'+(imgWidth+2)+';margin: 0px; padding:0px;height:'+(imgHeight+textFromHeight)+'px; overflow:hidden;}');
document.write('#txtFrom{height:'+textFromHeight+'px;line-height:'+textFromHeight+'px;width:'+imgWidth+'px;overflow:hidden;}');
document.write('#imgTitle{width:'+imgWidth+';top:-'+(textFromHeight+16)+'px;height:18px}');
document.write('</style>');
document.write('<div id="focuseFrom">');
//焦点字框高度样式表 结束
imgUrl[1]='http://www.pconline.com.cn/test/toptitle/images/picpath/20060918_1.jpg';
imgtext[1]='<A HREF="http://www.pconline.com.cn/network/0918/" TARGET="_blank" class="'+textLinkStyle+'">视频</A>';
imgLink[1]='http://www.pconline.com.cn/network/0918/';
imgAlt[1]='视频';
imgUrl[2]='http://www.pconline.com.cn/test/toptitle/images/picpath/060915_kpt1_365.jpg';
imgtext[2]='<A HREF="http://www.pconline.com.cn/pcedu/sj/pm/photoshop/lj/0609/868264.html" TARGET="_blank" class="'+textLinkStyle+'">软件宽屏</A>';
imgLink[2]='http://www.pconline.com.cn/pcedu/sj/pm/photoshop/lj/0609/868264.html';
imgAlt[2]='软件宽屏';
imgUrl[3]='http://www.pconline.com.cn/test/toptitle/images/picpath/geibaihuikuanpin_365x120.jpg';
imgtext[3]='<A HREF="http://www.pconline.com.cn/comm/chnews/comm060911/index.html" TARGET="_blank" class="'+textLinkStyle+'">通信</A>';
imgLink[3]='http://www.pconline.com.cn/comm/chnews/comm060911/index.html';
imgAlt[3]='通信';
function changeimg(n)
{
adNum=n;
window.clearInterval(theTimer);
adNum=adNum-1;
nextAd();
}
function goUrl(){
window.open(imgLink[adNum],'_blank');
}
//NetScape开始
if (navigator.appName == "Netscape")
{
document.write('<style type="text/css">');
document.write('.buttonDiv{height:4px;width:21px;}');
document.write('</style>');
function nextAd(){
if(adNum<(imgUrl.length-1))adNum++;
else adNum=1;
theTimer=setTimeout("nextAd()", TimeOut);
document.images.imgInit.src=imgUrl[adNum];
document.images.imgInit.alt=imgAlt[adNum];
    document.getElementById('focustext').innerHTML=imgtext[adNum];
document.getElementById('imgLink').href=imgLink[adNum];}
document.write('<a id="imgLink" href="'+imgLink[1]+'" target=_blank class="p1"><img src="'+imgUrl[1]+'" name="imgInit" width='+imgWidth+' height='+imgHeight+' border=1 alt="'+imgAlt[1]+'" class="imgClass"></a><div id="txtFrom"><span id="focustext" class="'+textStyle+'">'+imgtext[1]+'</span></div>')
document.write('<div id="imgTitle">');
document.write('<div id="imgTitle_down">');
//数字按钮代码结束
document.write('</div>');
document.write('</div>');
document.write('</div>');
nextAd();
}
//NetScape结束
//IE开始
else
{
var count=0;
for (i=1;i<imgUrl.length;i++) {
if( (imgUrl[i]!="") && (imgLink[i]!="")&&(imgtext[i]!="")&&(imgAlt[i]!="") ) {
count++;
} else {
break;
}
}
function playTran(){
if (document.all)
imgInit.filters.revealTrans.play();
}
var key=0;
function nextAd(){
if(adNum<count)adNum++ ;
else adNum=1;

if( key==0 ){
key=1;
} else if (document.all){
imgInit.filters.revealTrans.Transition=6;
imgInit.filters.revealTrans.apply();
                   playTran();
    }
document.images.imgInit.src=imgUrl[adNum];
document.images.imgInit.alt=imgAlt[adNum];
document.getElementById('link'+adNum).style.background=buttonLineOn;
for (var i=1;i<=count;i++)
{
   if (i!=adNum){document.getElementById('link'+i).style.background=buttonLineOff;}
}
    focustext.innerHTML=imgtext[adNum];
theTimer=setTimeout("nextAd()", TimeOut);
}
document.write('<a target=_self href="javascript:goUrl()"><img style="FILTER: revealTrans(duration=1,transition=5);" src="javascript:nextAd()" width='+imgWidth+' height='+imgHeight+' border=0 vspace="0" name=imgInit class="imgClass"></a>');
document.write('<div id="txtFrom"><span id="focustext" class="'+textStyle+'"></span></div>');
document.write('<div id="imgTitle">');
document.write(' <div id="imgTitle_down"> <a class="trans"></a>');
//数字按钮代码开始
for(var i=1;i<imgUrl.length;i++){document.write('<a id="link'+i+'" onmouseover="javascript:changeimg('+i+')"  class="button" style="cursor:hand" title="'+imgAlt[i]+'" onFocus="this.blur()">'+i+'</a>');}
//数字按钮代码结束
document.write('</div>');
document.write('</div>');
document.write('</div>');
}
//IE结束
</script>
</body>
</html>