function citys(){
    $('com_country').addEvent('change', function(){
       if ('' == this.getValue()) {
           $('china').setStyle('display','none');
           $('othercountrys').setStyle('display','none');
           $('com_state').setProperty('disabled',true);
           $('com_city').setProperty('disabled',true);
           $('com_city_other').setProperty('disabled',true);
       } else if ('中国' != this.getValue()) {
           $('china').setStyle('display','none');
           $('othercountrys').setStyle('display','inline');
           $('com_state').setProperty('disabled',true);
           $('com_city').setProperty('disabled',true);
           $('com_city_other').setProperty('disabled',false);
       } else {
           $('china').setStyle('display','inline');
           $('othercountrys').setStyle('display','none');
           $('com_state').setProperty('disabled',false);
           $('com_city').setProperty('disabled',false);
           $('com_city_other').setProperty('disabled',true);
       }
   });

   $('com_state').addEvent('change', function(){
       var url = "/ajax/city/index/com_state/"+encodeURIComponent(this.getValue());
       var jSonRequest = new Json.Remote(url, {onComplete: function(citylist){
           $('com_city').length = 1;
           for(i=0;i<citylist.length;i++){
               var option = new Option(citylist[i],citylist[i]);
               $('com_city').options.add(option);
           }
       }}).send(null);
   });
}