[求助]原码写完后，程序不运行的问题！

unit Unit12;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, Menus;

type
TfrmMain = class(TForm)
MainMenu1: TMainMenu;
N1: TMenuItem;
N2: TMenuItem;
N3: TMenuItem;
N4: TMenuItem;
N5: TMenuItem;
N6: TMenuItem;
N7: TMenuItem;
N8: TMenuItem;
N9: TMenuItem;
N10: TMenuItem;
N11: TMenuItem;
N12: TMenuItem;
N13: TMenuItem;
N14: TMenuItem;
N15: TMenuItem;
procedure N6Click(Sender: TObject);
procedure N9Click(Sender: TObject);
procedure N8Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
frmMain: TfrmMain;

implementation

uses Unit9,Unit10;

{$R *.dfm}

procedure TfrmMain.N6Click(Sender: TObject);
begin
close;
end;

procedure TfrmMain.N9Click(Sender: TObject);
begin
StudentForm.ShowModal;
end;

procedure TfrmMain.N8Click(Sender: TObject);
begin
SpecialityForm.ShowModal;
end;

end.



这是原代码。
还有一个问题，每次运行Unit12时，总是冒出Unit10，删除后，再运行，还是这样，这是为什么呢？