unit Unit1;interfaceuses  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,  Dialogs, ExtCtrls, StdCtrls;typeTMyThread = class(TThread)  private    { Private declarations }    procedure AddTh;    procedure DecTh;  protected    procedure Execute; override;  end;  TForm1 = class(TForm)    Edit1: TEdit;    Timer1: TTimer;    Button1: TButton;    procedure FormCreate(Sender: TObject);    procedure Timer1Timer(Sender: TObject);    procedure Button1Click(Sender: TObject);  private    { Private declarations }  public    { Public declarations }    ThCounter:integer;  end;var  Form1: TForm1;implementation{$R *.dfm}procedure TForm1.FormCreate(Sender: TObject);begin  ThCounter:=0;end;{ TMyThread }procedure TMyThread.AddTh;begin  Form1.ThCounter:= Form1.ThCounter +1;  Form1.Edit1.Text:= intToStr(Form1.ThCounter);end;procedure TMyThread.DecTh;begin  Form1.ThCounter:= Form1.ThCounter -1;  Form1.Edit1.Text:= intToStr(Form1.ThCounter);end;procedure TMyThread.Execute;var  i:integer;begin  inherited;  Synchronize(AddTh);  sleep(10000);  Synchronize(DecTh);end;procedure TForm1.Timer1Timer(Sender: TObject);var  th:TMyThread;beginif(Form1.ThCounter<5) thenbegin  th:= TMyThread.Create(true);  th.FreeOnTerminate:=true;  th.Resume();  end;end;procedure TForm1.Button1Click(Sender: TObject);beginTimer1.Enabled:=true;end;end.