/// <summary>
    /// 获取指定年月的第一天
    /// </summary>
    /// <param name="dt">日期</param>
    /// <returns></returns>
    public static DateTime GetCurMonthFirstDay(DateTime dt)
    {
        DateTime AssemblDate = Convert.ToDateTime(dt.Year + "-" + dt.Month + "-" + "01"); 
        return AssemblDate.AddDays(1 - AssemblDate.Day);
    }

    /// <summary>
    /// 获取指定年月的最后一天
    /// </summary>
    /// <param name="dt">日期</param>
    /// <returns></returns>
    public static DateTime GetCurMonthLastDay(DateTime dt)
    {
        DateTime AssemblDate = Convert.ToDateTime(dt.Year + "-" + dt.Month + "-" + "01");
        return AssemblDate.AddDays(1 - AssemblDate.Day).AddMonths(1).AddDays(-1);
    }