private void button1_Click(object sender, EventArgs e)
        {
            bool flag = false;
            if (iter < tasks.Count)
            {
                GroupBox g = tasks[iter].Controls.Find("gb", true).FirstOrDefault() as GroupBox;
                RadioButton tmp = new RadioButton();
                int i = 0;
                foreach (RadioButton r in g.Controls)
                {
                    if (r.Checked == true && questions[iter].answers[r] == true && !questions[iter].isAnswered)
                    {
                        cor_ans.Text = Convert.ToString(Int32.Parse(cor_ans.Text) + 1);
                        questions[iter].isAnswered = true;
                        flag = true;
                        break;
                    }
                    i++;
                }
                iter++;
            }
            if (!flag)
                button1.Enabled = false;
            if (iter < tasks.Count)
                ShowOnePanel(iter);

        }