cookie.Expires = DateTime.Now.AddMinutes(3);//设置分钟
cookie.Expires = DateTime.Now.AddDays(3);//设置3天后过期
cookie.Expires = DateTime.Now.AddHours(3);//设置3小时后过期
cookie.Expires = DateTime.Now.AddMinutes(3);//设置分钟
cookie.Expires = DateTime.Now.AddDays(3);//设置3天后过期
cookie.Expires = DateTime.Now.AddHours(3);//设置3小时后过期