19???100???400???200???? ??? ????? ?? ??? ????? ?? ??? ?? ??? ?? ?????? ?????? ??????? ?????? ?? ???? ??? ??? ?????. ????? ????? ??????? ?????? ?? ????? ?????? ?????? ??????? ??? ?????? ????? ???????.?????? ?? ?????? ?? ??????? ??????? ?? ?????? ???? ???? ????? ???. The “Three C’s” undoubtedly are a useful way to think about this. They expla