关于this的问题

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<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>导航菜单</title>
<style type="text/css">
* { margin: 0; padding: 0; font-size: 14px; }
a { color: #333; text-decoration: none }
ul { list-style: none; height: 30px; border-bottom: 5px solid #F60; margin-top: 20px; padding-left: 50px; }
ul li { float: left }
ul li a { display: block; height: 30px; text-align: center; line-height: 30px; width:120px; background: #efefef; margin-left: 1px; }
a.on, a:hover { background: #F60; color: #fff; }
</style>
<script>
window.onload=function(){
    var aA=document.getElementsByTagName('a');
   for(var i=0; i<aA.length; i++){
       aA[i].onmouseover=function(){
           var This=this;
           【任务1】(This.time);
           This.time=【任务2】(function(){
                   This.style.width=This.offsetWidth+8+"px";
                   if(This.【任务3】>=160)
                   clearInterval(This.time);
               },30)
       }
       aA[i].onmouseout=function(){
               clearInterval(this.time);
               var This=this;
               this.time=setInterval(function(){
                   This.style.width=This.offsetWidth-8+"px";
                   if(This.offsetWidth<=120){
                       This.style.width='120px';
                       clearInterval(This.time);
                   }
               },30)
       }
   }
}
</script>
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