??????????? ??? ??????????????? ???????? ????? ????????! ????? ??????? ?? ?????? ??????????? ?????? , ????? ???????? , ??? ????????? ??? ????? ??????? N??c ta ????????? : du l?ch ???????? ????? ???????? có ?????? n?i tuy?t ??p ?????? ???? môi tr??ng ????? . ng??i ta ???c phép ghé th?m {??????? ??????? ?????? ví d? nh?ng ??i ??? c?a th?