<!--把如下代码加入<body>区域中:-->
<SCRIPT>
<!--
function check(){ //remove this line to use the script for real
var from = document.referrer
var here = "http://www.knowsky.com/js/311.htm" //Change this to your site
alert("From:"+from);//remove this line to use the script for real
alert("Here:"+here);//remove this line to use the script for real
if (from.substring(0,here.length) != here) history.back()
else document.location.replace('http://www.knowsky.com/js/311.htm'); //Page to go to if OK
}//remove this line to use the script for real
//-->
</SCRIPT>
<FORM>
<INPUT TYPE=button VALUE="Check" onClick="check()">
</FORM>