function showTop(second_img,is_third){
	if(is_third){
		document.write("<div id='pku_logo'>");
		document.write("<div id='logo'><img src='../../images/2.gif'/></div>");
		document.write("<div id='menu'><ul><li><a href='#' style='visibility:hidden;'>ENGLISH</a><a href='#' style='visibility:hidden;'>北大地图</a><a href='http://www.pku.edu.cn' style='visibility:hidden;'>北大主页</a></li></ul></div>")
		document.write("<div id='pku_pho'><img src='../../images/second_10/"+second_img+".gif'  alt=''/></div>");
		document.write("<div id='pku_menu'><ul>");
		document.write("<li class='menu_b'><a href='../../index.html'>首&nbsp;&nbsp;&nbsp;&nbsp;页</a></li>");
		document.write("<li class='menu_a'><a href='../../zzjg/zzjg.html'>组织机构</a></li>");
		document.write("<li class='menu_a'><a href='../../hdzn/qxx.html'>活动指南</a></li>");
		document.write("<li class='menu_a'><a href='../../tzgg/tzgg.html'>通知公告</a></li>");
		document.write("<li class='menu_a'><a href='#'>寄语北大</a></li>");
		document.write("<li class='menu_a'><a href='../../bdxy/bdyc.html'>北大校友</a></li>");
		document.write("<li class='menu_a'><a href='../../xqdt/xqdt.html'>校庆动态</a></li>");
		document.write("<li class='menu_a'><a href='../../jrbd/xkfz.html'>今日北大</a></li>");
		document.write("<li class='menu_a'><a href='../../xqjz/jzdt.html'>校庆捐赠</a></li>");
		document.write("</ul></div>");
	}
	else{
		document.write("<div id='pku_logo'>");
		document.write("<div id='logo'><img src='../images/2.gif'/></div>");
		document.write("<div id='menu'><ul><li><a href='#' style='visibility:hidden;'>ENGLISH</a><a href='#' style='visibility:hidden;'>北大地图</a><a href='http://www.pku.edu.cn' style='visibility:hidden;'>北大主页</a></li></ul></div>")
		document.write("<div id='pku_pho'><img src='../images/second_10/"+second_img+".gif'  alt=''/></div>");
		document.write("<div id='pku_menu'><ul>");
		document.write("<li class='menu_b'><a href='../index.html'>首&nbsp;&nbsp;&nbsp;&nbsp;页</a></li>");
		document.write("<li class='menu_a'><a href='../zzjg/zzjg.html'>组织机构</a></li>");
		document.write("<li class='menu_a'><a href='../hdzn/qxx.html'>活动指南</a></li>");
		document.write("<li class='menu_a'><a href='../tzgg/tzgg.html'>通知公告</a></li>");
		document.write("<li class='menu_a'><a href='#'>寄语北大</a></li>");
		document.write("<li class='menu_a'><a href='../bdxy/bdyc.html'>北大校友</a></li>");
		document.write("<li class='menu_a'><a href='../xqdt/xqdt.html'>校庆动态</a></li>");
		document.write("<li class='menu_a'><a href='../jrbd/xkfz.html'>今日北大</a></li>");
		document.write("<li class='menu_a'><a href='../xqjz/jzdt.html'>校庆捐赠</a></li>");
		document.write("</ul></div>"); 
	}
}

function showLeft(index){
	var top_menu = new Array(9);
	top_menu[0]="组织机构";
	top_menu[1]="活动指南";
	top_menu[2]="通知公告";
	top_menu[3]="校史回眸";
	top_menu[4]="北大校友";
	top_menu[5]="校庆动态";
	top_menu[6]="今日北大";
	top_menu[7]="校庆捐赠";
	top_menu[8]="北大标志"
	
	var sub_menu=new Array(9);
	var sub_link=new Array(9);
	sub_menu[0]=new Array(0);
	sub_link[0]=new Array(0);
	sub_menu[1]=new Array("校庆主要活动","校庆系列活动","联系通讯录");
	sub_link[1]=new Array("./qxx.html","./ejdw.html","./fzr.html");
	sub_menu[2]=new Array(0);
	sub_link[2]=new Array(0);
	sub_menu[3]=new Array(0);
	sub_link[3]=new Array(0);
	sub_menu[4]=new Array("校友风采","情系母校","校友文萃","校友工作");
	sub_link[4]=new Array("./bdyc.html","./gamx.html","./jqbd.html","./xygz.html");
	sub_menu[5]=new Array(0);
	sub_link[5]=new Array(0);
	sub_menu[6]=new Array("学科发展","科研创新","师资力量","人才培养","校园文化","基础设施","对外交流","社会服务","校园环境","媒体北大");
	sub_link[6]=new Array("./xkfz.html","./kjcx.html","./szll.html","./rcpy.html","./xywh.html","./jcss.html","./dwjl.html","./shfw.html","./xyhj.html","./mtbd.html");
	sub_menu[7]=new Array("捐赠动态","捐赠项目","捐赠方式","鸣谢办法");
	sub_link[7]=new Array("./jzdt.html","./jzxm.html","./jzfs.html","./mxbf.html");
	sub_menu[8]=new Array(0);
	sub_link[8]=new Array(0);
	
	document.write("<div id='left_menu'>");
	document.write("<ul><li class='top_menu'>"+top_menu[index-1]+"</li></ul><ul>");
	for(var i=0;i<sub_menu[index-1].length;i++){
		document.write("<li class='sub_menu'><a href='"+sub_link[index-1][i]+"'>"+sub_menu[index-1][i]+"</a></li>");
	}
	document.write("</ul></div>");
}

function showTimeDown(){
	var xmlhttp = false; 
	try	{ 
		    xmlhttp = new ActiveXObject("MSXML2.XMLHTTP"); 
		} 
		catch(e) 
		{ 
		    try 
		    { 
		        xmlhttp = new ActiveXObject("Microsoft.XMLHTTP"); 
		    } 
		    catch(e2){xmlhttp = false;} 
		} 
	if (!xmlhttp && typeof XMLHttpRequest!='undefined') {
		try {
			xmlhttp = new XMLHttpRequest();
		} catch (e) {
			xmlhttp=false;
		}
	}
	if (!xmlhttp && window.createRequest) {
		try {
			xmlhttp = window.createRequest();
		} catch (e) {
			xmlhttp=false;
		}
	}
	
	var now;
	try{
		xmlhttp.open("GET", "http://www.pku.edu.cn/", false);//注意，此处要修改成部署服务器地址
		xmlhttp.setRequestHeader("If-Modified-Since","q"); 
		xmlhttp.send(null); 
		
		var dateStr=xmlhttp.getResponseHeader("Date"); 
		now=new Date(dateStr); 
		if(isNaN(now))
			now = new Date(); //如果无法获得，用客户端的
	}catch (e) {
		now = new Date(); //连不上，用客户端的
	}
	var oly = new Date(2008,4,4,0,0,0,0);
	var dis = oly-now;
	var days = Math.ceil(dis/(1000*60*60*24));
	document.write("距北京大学110周年校庆还有<span>"+days+"</span>天");
}
var i=1;
function showRandomImg(){
	i++;
	if(i>4)	i=1;
	document.getElementById("titleImg").src="images/main_img/t"+i+".gif";
}
function showTitleImg(){
	setInterval("showRandomImg()",5000);
}