var how_many_ads = 3;
var now = new Date()
var sec = now.getSeconds()
var ad = sec % how_many_ads;
ad +=1;
if (ad==1) {
txt="AD:风水用品专卖";
url="http://www.upjx.com";
alt="上上吉祥网";
banner="http://files.18zw.com/upjx.jpg";
width="680";
height="200";
}
if (ad==2) {
txt="AD:和玉文化传播 ";
url="http://www.heyu-china.com";
alt=" 和玉设计";
banner="http://files.18zw.com/images/heyu.jpg";
width="680";
height="200";
}
if (ad==3) {
txt="AD：观星殿内部资料"; 
url="http://shop58096385.taobao.com/?catId=148607445&queryType=cat&categoryName=udvQx7XuxNqyv9fKwc8%3D&encodeCategoriesName=y&search=y";
alt="斗数书《观星殿》";
banner="http://files.18zw.com/gxd.jpg";
width="666";
height="235";
}
document.write("<center>");
document.write("<a href=\"" + url + "\" target=\"_top\">");
document.write("<img src=\"" + banner + "\" width=")
document.write(width + " height=" + height + " ");
document.write("alt=\"" + alt + "\" border=0><br>");
document.write("<small>" + txt + "</small></a>");
document.write("</center>");