The obstacle lies in basically obtaining the abilities and information required to master this subject. Here are several of An important measures:?? ????? ??????? ?????? ???? ??? ?????? ?? ???? ????, ?? ????, ????? ?????? ??????? ????? ???????? ?????? – ??? ??????? ???? ????, ?? ?? ???? ????? ??? ?? ???? ?????? ????? ??? ??????? ????? (?? ????, ?