var p=2;  //Ëæ»úÊýµÄ·¶Î§
var q=Math.floor(Math.random()*p+1)
switch(q) {
   case 1:
   document.write('<script src="/float2.js" language="javascript"></script>');
   break;

   case 2:
   document.write('<script src="/float2.js" language="javascript"></script>');
   break;
}