How to enable shortcuts in child form

I have wrote a frame application, it's a windows form app as parent form.When it starts, it will find dlls in /modules and load them as extensions. And when I click the menuItem in the parent form, the specific dll will work.If the dll is a Form app, it will show.But when i try to use shortcuts(only build-ins,eg : CTRL-C...) in the childForm ,the hotkeys does not work. Anyone kindly tell me why and how can i fix the issue? Here's my code:

//parent.exe--ModuleEntrance.cs
public abstract class ModuleEntrance {
  public abstract string[] GetMenuNames();
  public abstract string[] GetMenuItemNames();
  public abstract EventHandler[] GetEventHandlers();
}
//parent.exe--ParentForm.cs
public partial class MDIParent : Form {
  public MDIParent() { //CTOR
    InitializeComponent();
    ModuleEntrance oneEntrance;
    string oneMenuName, oneMenuItemName;
    ToolStripMenuItem theMenu, theMenuItem;
    for(){ //iterate dlls in /modules, if it implement ModuleEntrance, load it. 
          //And 1)load menu&menuItem.  
          //2) connect handler to menuItem.click through 
        //<code:theMenuItem.Click += new EventHandler(oneEntrance.GetEventHandlers()[i]);>
    }
}

//--------------
//child.dll-- EntranceImp.cs  //implement AC
public class EntranceImp : ModuleEntrance {
  public override string[] GetMenuNames() {
    return new string[] { "MEN开发者_StackOverflowU"};
  }
  public override string[] GetMenuItemNames() {
    return new string[] { "OpenChildForm"};
  }
  public override EventHandler[] GetEventHandlers() {
    return new EventHandler[]{
      (EventHandler)delegate(object sender, EventArgs e) { //Anonymous method
        childForm form = new childForm();
        //find MDIparent and connect them
        ToolStripMenuItem mi = (ToolStripMenuItem)sender;
        form.MdiParent = (Form)(mi.OwnerItem.Owner.Parent);  //It works!
        form.Show();
      }
    };
  }
}
//child.dll--childForm.dll
//...

The child form has to notify the parent form about the key-down events somehow.

A way to do this is to have the child form expose key-down events that the parent form can listen to. Remember to remove the parent event handlers every time that you change child form, or you'll end up with a memory leak since objects are not garbage collected until you release all references to them, including event handlers.

class Parent
{
    KeyEventHandler KeyDownHandler;

    public Parent()
    {
        KeyDownHandler = new KeyEventHandler(form_TextBoxKeyDown);
    }

    void SetChildForm(Child form)
    {
        form.TextBoxKeyDown += KeyDownHandler;
    }

    void RemoveChildForm(Child form)
    {
        form.TextBoxKeyDown -= KeyDownHandler;
    }

    void form_TextBoxKeyDown(object sender, KeyEventArgs e)
    {
        if (e.Control)
        {
            switch (e.KeyCode)
            {
                case Keys.C:

                    break;
                case Keys.X:

                    break;
                case Keys.V:

                    break;
            }
        }
    }
}

class Child
{
    TextBox txtBox;

    public event KeyEventHandler TextBoxKeyDown;

    internal Child()
    {
        txtBox.KeyDown += new KeyEventHandler(txtBox_KeyDown);
    }

    void txtBox_KeyDown(object sender, KeyEventArgs e)
    {
        if (TextBoxKeyDown != null)
            TextBoxKeyDown(sender, e);
    }
}