private void thốngKêBiểuĐồToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Bieu_do bd = new Bieu_do();

            bd.Show();
        }
        private void biểuĐồToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Bieu_do bieudo = new Bieu_do();

            bieudo.Show();
        }