private void radButton1_Click(object sender, EventArgs e)
        {
            offlinePasswd = new OfflinePasswdForm();
            offlinePasswd.ShowDialog(); //获得离线密码
            if (offlinePasswd.DialogResult == DialogResult.Cancel)
            {
                return;
            }
            ListBox.SelectedObjectCollection checkedToDownload = listBox1.SelectedItems;
            //选择的那门课程

            ____fDataModule.ServerToBriefcase
                (Properties.Settings.Default.CurrentDownloadPasswd, checkedToDownload);
            //开始下载课程信息
        }