Компонент ComboBox

  City[0].Items/Add('Воронеж');
  City[0].Items/Add('Белгород');
...
  City[0].Items/Add('Томск');
 
  City[1].Items/Add('Киев');
  City[1].Items/Add('Харьков');
...
  City[1].Items/Add('Одесса');

unit Unit1;
 
interface
 
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;
 
type
  TForm1 = class(TForm)
    ComboBox1: TComboBox;
    ComboBox2: TComboBox;
    procedure FormCreate(Sender: TObject);
    procedure ComboBox1Change(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
 
var
  Form1: TForm1;
 
implementation
 
{$R *.dfm}
 
var
  City : array[0..6] of TStringList; // êîëè÷åñòâî ñïèñêîâ ñ ãîðîäàìè - 1
  Citys : array[0..6] of TStringList; // êîëè÷åñòâî ñïèñêîâ ñ ãîðîäàìè - 1
 
procedure TForm1.FormCreate(Sender: TObject);
var
  I : Integer;
begin
 
  for I:= 0 to 4 - 1 do
    City[I] := TStringList.Create;
    City[1].Add('Áåëîðóññèÿ');
City[2].Add('Ðîññèÿ');
City[3].Add('Óêðàèíà');
 
end;
 
procedure TForm1.ComboBox1Change(Sender: TObject);
var
  I : Integer;
begin
 
  for I:= 0 to 4 - 1 do
    ComboBox2.Clear;
  ComboBox2.Items.AddStrings(City[ComboBox1.ItemIndex]);
    Citys[I] := TStringList.Create;
a         Citys[1].Add('Ìèíñê');
end;
 
end.