????? ?????? ???? ??? ??????? ??????? ??????? ?????? ??? ????? ???? ????? ????? ?? ?????.???? ??????? ????? ?? ??????? ???????? ??? ????? ??? ????? ? ????? ??????? ?????? ??? ????? ????? .??? ??? ??????? ??? ??????? ?????? ????? ????? ?? ??????Battery-operated detectors are easy to install, ordinarily needing only a few screws to mount to walls or