function verif_form(nb){
		var form = document.contact;
		var input = form.getElementsByTagName('input');
		if(form.getElementsByTagName('input')[nb].value==""){
			document.images['img'+nb].src = "/img/wrong.jpg";
			return false;
			
		}else{
			if(nb==2){
				if(form.getElementsByTagName('input')[nb].value.search(/^[_a-z0-9-]+(.[_a-z0-9-]+)*[^._-]@[a-z0-9-]+(.[a-z0-9]{2,4})*$/)==-1){
					document.images['img'+nb].src = "/img/wrong.jpg";
					alert("您的电子邮件地址格式不正确哦");
					return false;
				}else{
					document.images['img'+nb].src = "/img/clean.jpg";
				}
				
			}else if(nb==3){
				if(form.getElementsByTagName('input')[nb].value.search(/^[0-9-]*$/)==-1){
					document.images['img'+nb].src = "/img/wrong.jpg";
					alert("请输入您的联系电话");
					return false;
				}else{
					document.images['img'+nb].src = "/img/clean.jpg";
				}
				
			}else if(nb==4){
				if(form.getElementsByTagName('input')[nb].value==""){
					document.images['img'+nb].src = "/img/wrong.jpg";
					alert("请输入验证码");
					return false;
				}else{
					document.images['img'+nb].src = "/img/clean.jpg";
				}
				
				
			}else{
				document.images['img'+nb].src = "/img/clean.jpg";
			}
		}
		return true;
	}
	
	function valid_form(){
		var tab_img = new Array("0","2","3","4");
		for(i=0;i<=4;i++){
			var img = document.images['img'+tab_img[i]].src;
			var taille = img.length;
			var slash = img.lastIndexOf('/', taille);
			var fin = img.substring(slash+1,taille);
			if(fin!="clean.jpg"){
				document.images['img'+tab_img[i]].src = "/img/wrong.jpg";
				return false;
			}
		}
		return true;
	}