const int SECOND = 1;  const int MINUTE = 60 * SECOND;  const int HOUR = 60 * MINUTE;  const int DAY = 24 * HOUR;  const int MONTH = 30 * DAY;    if (delta < 0)  {    return "not yet";  }  if (delta < 1 * MINUTE)  {    return ts.Seconds == 1 ? "1秒前" : ts.Seconds + "秒前";  }  if (delta < 2 * MINUTE)  {    return "1分钟之前";  }  if (delta < 45 * MINUTE)  {    return ts.Minutes + "分钟";  }  if (delta < 90 * MINUTE)  {    return "1小时前";  }  if (delta < 24 * HOUR)  {    return ts.Hours + "小时前";  }  if (delta < 48 * HOUR)  {    return "昨天";  }  if (delta < 30 * DAY)  {    return ts.Days + " 天之前";  }  if (delta < 12 * MONTH)  {    int months = Convert.ToInt32(Math.Floor((double)ts.Days / 30));    return months <= 1 ? "一个月之前" : months + "月之前";  }  else  {    int years = Convert.ToInt32(Math.Floor((double)ts.Days / 365));    return years <= 1 ? "一年前" : years + "年前";  }