private void mnuNewScore_Click(object sender, EventArgs e)
 {
     if (BusinessRuler.Classes.IsClassExists())
     {
         FrmChooseClass frmChoose = new FrmChooseClass("成绩管理");
         frmChoose.ShowDialog();
     }
 }
 private void mnuBrowseStudent_Click(object sender, EventArgs e)
 {
     if (BusinessRuler.Classes.IsClassExists())
     {
         FrmChooseClass frmChoose = new FrmChooseClass("学生管理");
         frmChoose.ShowDialog();
     }
 }