private void bánVéToolStripMenuItem_Click(object sender, EventArgs e)
 {
     BanVeChuyenBay f = new BanVeChuyenBay();
     f.Show();
 }
 private void btnbanve_Click(object sender, EventArgs e)
 {
     BanVeChuyenBay f = new BanVeChuyenBay();
     f.Show();
 }