private void 修改学生信息ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            string[] str = { dataGridView1.SelectedCells[0].Value.ToString(), dataGridView1.SelectedCells[1].Value.ToString(), dataGridView1.SelectedCells[2].Value.ToString(), dataGridView1.SelectedCells[3].Value.ToString(), dataGridView1.SelectedCells[4].Value.ToString() };

            Form21 f = new Form21(str, this);

            f.ShowDialog();
        }
        private void 添加学生信息ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Form21 f = new Form21(this);

            f.ShowDialog();
        }