DataGridViewComboBoxCell cell =(DataGridViewComboBoxCell)dataGridView1[e.ColumnIndex, e.RowIndex];
cell.DisplayStyle=DataGridViewComboBoxDisplayStyle.Nothing;
cell.ReadOnly=true;
DataGridViewComboBoxCell cell =(DataGridViewComboBoxCell)dataGridView1[e.ColumnIndex, e.RowIndex];
cell.DisplayStyle=DataGridViewComboBoxDisplayStyle.Nothing;
cell.ReadOnly=true;