求救，这里的代码要怎么写，才能让链接失效的状态变为链接有效？

<html><head>
<script language="javascript">
window.onload = function() {

    document.getElementById('btn').onclick = function() {
        document.getElementById('down_load_false').style 这里的代码要怎么写，才能让链接失效的状态变为链接有效？
    }
}</script></head><body>
<div id="down_load_false"  style="a {poorfish:expression(this.onclick=function kill(){return false})}">
<a href="http://www.163.com">www.163.com</a>
</div>
<input type="button" id="btn" value="接触锁定" /> </body></html>

解决方案 »

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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style>
a {poorfish:expression(this.onclick=function kill(){return false;})}
</style>
</head><body>
<div id="down_load_false">
<a href="http://www.163.com">www.163.com</a>
</div>
<input type="button" id="btn" value="接触锁定" /><script language="javascript">
window.onload = function() {

    document.getElementById('btn').onclick = function() {
document.getElementById('down_load_false').onclick = function(){return true;}
        //document.getElementById('down_load_false').style 这里的代码要怎么写，才能让链接失效的状态变为链接有效？
    }
}</script>
</body>
</html>
<style>没有写在<div id="down_load_false">里，没用
<script language="javascript">
window.onload = function() {
    document.getElementById('btn').onclick = function() {
        document.getElementById('kk').onclick=function(){return true;};
    }
}
</script>
</head><body>
<div id="down_load_false">
<a id="kk" href="http://www.163.com" onclick="return false">www.163.com</a>
</div>
<input type="button" id="btn" value="解除锁定" />
<script language="javascript">
window.onload = function() {
  document.getElementById('kk').onclick=function(){return false;};
  document.getElementById('btn').onclick = function() {
  document.getElementById('kk').onclick=function(){return true;};
  }
}
</script>
</head><body>
<div id="down_load_false">
<a id="kk" href="http://www.163.com">www.163.com</a>
</div>
<input type="button" id="btn" value="解除锁定" />