?? ?? ??????? ????? ?? ????? ?????? ?? {?????? ?? ?? ??? ?? ?? ?????? ?????? ?? ?? ???? ????? ?? ??? ?? ????? ???? ?? ???? ??? ????? ????? ???? ????? ????? ???? AN ESSENTIAL TOOL ???? ?? ??? ?? IS INVOLVED IN REPAIR WORKS. ????? ????? ???? A CHAIR WITH ADJUSTABLE HEIGHT? ?? ????? ??? ????? ?? ALLOWS ?? IN DIFFERENT POSITIONS PERFORM THEIR DUTIES