private void LoadFormChonDeThiThu() { lbTenHocSinh.Text = hocSinhLogin.HoTen; List <DeVaCauHoiDTO> danhSachDeVaCauHoi = new List <DeVaCauHoiDTO>(); try { danhSachDeVaCauHoi = hocSinhBUS.GetAllDeThi(hocSinhLogin.MaHocSinh); } catch (Exception Ex) { MessageBox.Show(Ex.Message, "Exception Error!", MessageBoxButtons.OK, MessageBoxIcon.Error); } List <string> danhSachDoKho = LayDanhSachDoKho(danhSachDeVaCauHoi); if (danhSachDeVaCauHoi != null) { cbbChonMucDo.DataSource = danhSachDoKho; } List <De> danhSachDe = new List <De>(); danhSachDe = hocSinhBUS.LayDanhSachDe(cbbChonMucDo.Text, hocSinhLogin.MaHocSinh); if (danhSachDe != null) { cbbChonDeThi.DataSource = danhSachDe; cbbChonDeThi.DisplayMember = "TenDe"; cbbChonDeThi.ValueMember = "MaDe"; } else { cbbChonDeThi.Text = "Chưa có đề thi"; } }