void HienThiMaThietBi()
{
List <ThietBi> dsThietBi = tbbus.DanhSachThietBi();
string line;
foreach (var item in dsThietBi)
{
line = item.Mathietbi;
cbMaTB.Items.Add(line);
}
}
void DanhSachThietBi()
{
dgvThietBi.DataSource = tbBus.DanhSachThietBi();
}