case 2:
                SqlDataAdapter myadapter2 = new SqlDataAdapter("select * "
                    + "from tb_Questions where que_type='多选题'and que_lessonid='"
                    + dd1 + "'and que_taotiid='" + dd2 + "'order by id desc", con);
                DataSet myds2 = new DataSet();
                myadapter2.Fill(myds2);
                DataList2.DataSource = myds2;
                DataList2.DataBind();
                //生成多选题题号
                for (int tID2 = 1; tID2 <= DataList2.Items.Count; tID2++)
                {
                    Label lblDSelect = (Label)DataList2.Items[tID2 - 1].FindControl("Label24");
                    lblDSelect.Text = tID2.ToString() + "、";
                }
                break;
            //核对单选题答案
            case 3:
                SqlDataAdapter myadapter3 = new SqlDataAdapter("select id,que_answer"
                    + " from tb_Questions where que_type='单选题'and que_lessonid="
                    + dd1 + " and que_taotiid=" + dd2 + " order by id desc", con);
                DataSet myds3 = new DataSet();
                myadapter3.Fill(myds3);
                DataRow[] row1 = myds3.Tables[0].Select();
                //计算单选题成绩
                foreach (DataRow answer1 in row1)
                {
                    int_row1 += 1;
                    if (int_row1<= 3)
                    {
                        RadioButtonList rbl = (RadioButtonList)(DataList1.Items[int_row1 - 1].FindControl("RadioButtonList1"));
                        if (rbl.SelectedValue == "")
                        {
                            this.lblSel.Text = "0";
                        }
                        else
                        {
                            if (answer1["que_answer"].ToString().Trim() == rbl.SelectedValue.ToString().Trim())
                            {
                                int_row1Point += 40 / DataList1.Items.Count;
                                this.lblSel.Text = int_row1Point.ToString();
                            }
                        }
                    }
                }
                break;
            //核对多选题答案
            case 4:
                SqlDataAdapter myadapter4 = new SqlDataAdapter("select id,que_answer"
                    + " from tb_Questions where que_type='多选题'and que_lessonid="
                    + dd1 + " and que_taotiid=" + dd2 + " order by id desc", con);
                DataSet myds4 = new DataSet();
                myadapter4.Fill(myds4);
                DataRow[] row2 = myds4.Tables[0].Select();
                //计算多选题成绩
                foreach (DataRow answer2 in row2)
                {
                    int_row2 += 1;
                    if (int_row2 <= 3)
                    {
                        CheckBoxList cbl = (CheckBoxList)(DataList2.Items[int_row2 - 1].FindControl("CheckBoxList1"));
                        if (cbl.SelectedValue == "")
                        {
                            lblDSel.Text = "0";
                        }
                        else
                        {
                            this.TextBox1.Text = "";
                            for (int q = 0; q < cbl.Items.Count; q++)
                            {
                                if (cbl.Items[q].Selected == true)
                                {
                                    this.TextBox1.Text = TextBox1.Text.Trim() + cbl.Items[q].Value + ", ";
                                }
                            }
                            if (answer2["que_answer"].ToString().Trim() + "," == this.TextBox1.Text.Trim())
                            {
                                int_row2Point += 60 / DataList2.Items.Count;
                                this.lblDSel.Text = int_row2Point.ToString();
                            }
                        }
                    }
                }
                break;
这段考试的代码什么意思，我要最具体详细的解释啊，int_row1<= 3为什么要小于3,4、5、6不行吗？这个是不是就是单选最多的题目数。要很详细的注释包括每一行什么意思。

考生只能考一次这个问题。应该能考很多门课程，这个怎么改string sqlstr1 = "select count(*) from tb_StuResult where stu_id ='" + Session["StuName"] + "' and which_lesson='" + this.ddlSelLess.SelectedItem.Text + "'";（选择套题那页面）我改成这样，还是错，说没有引用实例什么的。我要具体代码和页面，知道这么改，我就是不知道代码。
哪个高手会，发我邮箱也行，谢谢了