//µ¼º½menuµÄЧ¹û add at 2011.9.02 by wgl.

$(document).ready(function(){
  $('li.mainlevel').mousemove(function(){
  $(this).addClass('active');
  $(this).find('ul').slideDown("1000");//you can give it a speed
  });
  $('li.mainlevel').mouseleave(function(){
  $(this).removeClass('active');
  $(this).find('ul').slideUp("fast");

  });
  
});