C# PlaceHolder

 protected void Page_Load(object sender, EventArgs e)
    {
        Label myLabel = new Label();
        TextBox mytxt1 = new TextBox();
        DropDownList dp01 = new DropDownList();

        // Set the label's Text and ID properties.
        myLabel.Text = "Label123";
        myLabel.ID = "Label123";
        PlaceHolder1.Controls.Add(myLabel);
        // Add a spacer in the form of an HTML <br /> element.
        PlaceHolder1.Controls.Add(new LiteralControl("<br />"));
        mytxt1.ID = "mytxt1";
        mytxt1.Text = "";
        PlaceHolder1.Controls.Add(new LiteralControl("<br />"));
        //dp01.DataBind();
        dp01.Items.Insert(0, new ListItem("Select a store", ""));
        dp01.Items.Insert(1, new ListItem("AAA", ""));
        dp01.Items.Insert(2, new ListItem("BBB", ""));
        PlaceHolder1.Controls.Add(mytxt1);

        PlaceHolder1.Controls.Add(new LiteralControl("<br />"));
        PlaceHolder1.Controls.Add(dp01);
        PlaceHolder1.Controls.Add(new LiteralControl("<br />"));

        //CheckBox
        CheckBoxList ckL01 = new CheckBoxList();
        ckL01.Items.Insert(0, new ListItem("please check point:", ""));
        ckL01.Items.Insert(1, new ListItem("point 001", "point001"));
        ckL01.Items.Insert(2, new ListItem("point 002", "point002"));
        ckL01.Items.Insert(3, new ListItem("point 003", "point003"));
        PlaceHolder1.Controls.Add(ckL01);

        //botton
        for (int i = 1; i <= 10; i++)
        {
            LinkButton olbtn = new LinkButton();
            olbtn.ID = "lbtn" + i;
            olbtn.Text = "測試按鈕" + i;
            olbtn.Click += new EventHandler(lbtn_Click);
            PlaceHolder1.Controls.Add(olbtn);

            Label olab = new Label();
            olab.Text = " | ";
            PlaceHolder1.Controls.Add(olab);

        }




    }

    protected void lbtn_Click(object sender, EventArgs e)
    {
        LinkButton lbtn = (LinkButton)sender;

        Response.Write("按鈕事件觸發：" + lbtn.ID);
       // Label123.Text = "成功";

    }