?? ????????????????????????
????:1????????????:??????????
2????????
3???????
4??????????
5????????
??????????????????????????????!
????
???
“???????”“??”
?????“?????????”
??
?????????????
?????
?????????=??(?????)??+????????+???????
?????
???????????????,?????????????,?????????,?????
???????:????????????????????????????????“??????????????”?
???
??????????
??????????,???????????????????????????????????,???????(?/?),?,?????????????????
?????
??????????,???????????
???????????????????????????????
????,??????????????????????
???????
?????????????,????????
?????????????????????????
????,?????????4500?,??????4200??,?????3600????,????????????????300?????
????300?????
??????????,??????????????????????,?????4200????????????-3600???=600??????
????
?
????
“????”?????????
?????????
?????????
“??????????”????
?????????
??????
???????:“?”?????????????????
????:????