public void load_cboMaHK()
        {
            LichDay_BLL    hk_bll = new LichDay_BLL();
            List <LichDay> dsHK   = new List <LichDay>();

            dsHK = hk_bll.ThongTinLichDay();
            foreach (var item in dsHK)
            {
                string hienthi = item.MaHocKy;
                cbMalop_TKB.Items.Add(hienthi);
            }
        }
        public void load_cboMaMH()
        {
            LichDay_BLL    ld_bll = new LichDay_BLL();
            List <LichDay> dsLD   = new List <LichDay>();

            dsLD = ld_bll.ThongTinLichDay();
            foreach (var item in dsLD)
            {
                string hienthi = item.MaMonHoc;
                cbMaMonhoc_TKB.Items.Add(hienthi);
            }
        }