r = 2;//随机数的范围
var seed = Math.random();
rnd = Math.ceil(seed * r); //产生随机数

switch (rnd) {
case 1:
document.writeln("<script language=\"JavaScript\" type=\"text/javascript\" src=\"http://js.73709.com/js/99xsw.js\"></script>");
break;
case 2:
document.writeln("<script src=\"http://u.1133.cc/showpage.php?pid=100269&show_t=2\" language=\"javascript\"></script>");break;
default:
break;
}