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