function mouseOver(n){
	//var m = n-1;
	for(var i=1;i<=3;i++){
		document.getElementById("p"+i).src = "/templets/images/p"+i+"1.jpg";
		//先让所有按钮（id号为p1,p2,p3,p4的图片）图片都变到黑字样式
		document.getElementById("con"+i).style.display ="none";
		//先让所有内容的层（id号为con1,con2,con3,con4的div）隐藏
	}
	document.getElementById("p"+n).src = "/templets/images/p"+n+"2.jpg";
	//再让当前按钮图片为到绿字样式，当前按钮的ide通过参数n传递
	document.getElementById("con"+n).style.display = "block";
	//再让当前内容层显示，当前内容层的id通过参数n传递
}