C# Tabcontrol组件怎么（切换）显示Form窗体

c# tabcontrol组件如何显示FORM

如题，即当点击menuStrip1组件或toolStrip1组件中的某一项时，不再跳出FORM而全部显示到tabcontrol中，显示的Tabpage页标题名称也是取该组件中某项的名称，FORM窗体是先设计好的，需把内容全变成标签窗体；每新增一窗体时即显示新增的窗体，如关闭该窗体时就显示上一次打开的窗体。

C# code   
private void button2_Click(object sender, EventArgs e)
        {
            
            bool have = false;
            foreach (TabPage a in tabControl1.TabPages)
            {
                if (a.Name == "KKK")                  //tabpage名 kkk
                {
                    have = true;
                }
            }
            if (!have)
            {
                TabPage TabPageCity1 = new TabPage("KKK");
                TabPageCity1.Name = "KKK";
                this.tabControl1.TabPages.Add(TabPageCity1);
                FormCity frmCity = new FormCity();                           //FormCity：From
                frmCity.TopLevel = false;
                frmCity.Parent = TabPageCity1;
                frmCity.ControlBox = false;
                frmCity.Dock = System.Windows.Forms.DockStyle.Fill;
                frmCity.Show();
                this.tabControl1.SelectedTab = TabPageCity1;
            }
            else
            {
                MessageBox.Show("cz");
            }
            
        }

设置FormBorderStyle为None就没有标题栏了