function chkemail(email){
if (email==""){
	alert ("请输入您的电子邮件地址！");
	return false;
	}
else{
	if (email.substring(0,1)=="@"||email.substring(email.length-1,email.length)=="@"||email.substring(0,1)=="."||email.substring(email.length-1,email.length)=="."){
		alert ("请输入正确的E-Mail！");
		return false;
		}
	var j=0;
	for (var i=0;i<email.length;i++){
		temp="" + email.substring(i,i+1);
		if (temp=="@"){
			j=j+1;
			}
		}
	if (j!="1"){
		alert ("请输入正确的E-Mail！");
		return false;
		}
	email_temp = email.split("@")
	email_array=email_temp[1].split(".")
	if (email_array[1].length!="2"&&email_array[1].length!="3"){
		alert ("请输入正确的E-Mail！");
		return false;
		}
	j=0;
	for (i=0;i<email_temp[1].length;i++){
		temp="" + email_temp[1].substring(i,i+1);
		if (temp=="."){
			j=j+1;
			}
		}
	if (j=="0"){
		alert ("请输入正确的E-Mail！");
		return false;
		}
	for (i=0;i<email_temp[1].length-1;i++){
		temp="" + email_temp[1].substring(i,i+2);
		if (temp==".."){
			alert ("请输入正确的E-Mail！");
			return false;
			}
		}
	}
}