function img_on(m,divName){

	var name1 = document.getElementById(divName);
	var name2 = name1.getElementsByTagName("span");
	for (var i=0;i<name2.length ;i++ )
	{
		name2[i].getElementsByTagName("img")[0].setAttribute("src","http://cms.5ding.com/skins/default/xingke/images/arrow_"+(i+1)+".gif");
		document.getElementById(divName+i).style.display="none";

	}

		name2[m].getElementsByTagName("img")[0].setAttribute("src","http://cms.5ding.com/skins/default/xingke/images/arrow_on"+(m+1)+".gif");
		document.getElementById(divName+m).style.display="block";


}