if MessageDlg('Welcome to my Delphi application. Exit now?', 
mtConfirmation, [mbYes, mbNo], 0) = mrYes then
begin
 
Close; 
end;

procedure TForm1.Button1Click(Sender: TObject);
var
S:string;
begin
if MessageDlg('提示框',mtInformation,[mbok,mbyes],0)=mryes then
      messagebeep(MB_ICONEXCLAMATION);
end;
TMsgDlgType = (mtWarning, mtError, mtInformation, mtConfirmation, mtCustom);
TMsgDlgBtn = (mbYes, mbNo, mbOK, mbCancel, mbAbort, mbRetry, mbIgnore,    mbAll, mbNoToAll, mbYesToAll, mbHelp);
constmrNone     = 0;mrOk       = idOk;mrCancel   = idCancel;mrAbort    = idAbort;mrRetry    = idRetry;
mrIgnore   = idIgnore;mrYes      = idYes;mrNo       = idNo;mrAll      = mrNo + 1;mrNoToAll = mrAll + 1;mrYesToAll = mrNoToAll + 1;

SMsgDlgWarning = 'Warning'; 
SMsgDlgError = 'Error'; 
SMsgDlgInformation = 'Information'; 
SMsgDlgConfirm = 'Confirm'; 
SMsgDlgYes = '&Yes'; 
SMsgDlgNo = '&No'; 
SMsgDlgOK = 'OK'; 
SMsgDlgCancel = 'Cancel'; 
SMsgDlgHelp = '&Help'; 
SMsgDlgHelpNone = 'No help available'; 
SMsgDlgHelpHelp = 'Help'; 
SMsgDlgAbort = '&Abort'; 
SMsgDlgRetry = '&Retry'; 
SMsgDlgIgnore = '&Ignore'; 
SMsgDlgAll = '&All'; 
SMsgDlgNoToAll = 'N&o to All'; 
SMsgDlgYesToAll = 'Yes to &All';

SMsgDlgWarning = '警告'; 
SMsgDlgError = '错误'; 
SMsgDlgInformation = '提示'; 
SMsgDlgConfirm = '确认'; 
SMsgDlgYes = '是(&Y)'; 
SMsgDlgNo = '不(&N)'; 
SMsgDlgOK = '确定'; 
SMsgDlgCancel = '取消'; 
SMsgDlgHelp = '帮助(&H)'; 
SMsgDlgHelpNone = '没有该帮助信息'; 
SMsgDlgHelpHelp = '帮助'; 
SMsgDlgAbort = '放弃(&A)'; 
SMsgDlgRetry = '重试(&R)'; 
SMsgDlgIgnore = '忽略(&I)'; 
SMsgDlgAll = '全部(&A)'; 
SMsgDlgNoToAll = '全都不(&O)'; 
SMsgDlgYesToAll = '全都是(&A)';