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          if (dataGridView1.Rows[e.RowIndex].IsNewRow)
            {
                var lvvon = dataGridView1.Rows[e.RowIndex].Cells[1].Value;
                var lvbis = dataGridView1.Rows[e.RowIndex].Cells[2].Value;
                if (lvvon == null || lvbis == null)
                {

                    DataGridViewComboBoxCell cell = (DataGridViewComboBoxCell)dataGridView1[e.ColumnIndex, e.RowIndex];
                    cell.ReadOnly = true;
                }
                else
                {
                    DataGridViewComboBoxCell cell = (DataGridViewComboBoxCell)dataGridView1[e.ColumnIndex, e.RowIndex];
                    cell.ReadOnly = false;

                }