???????2??18?????????? (???????????? ?????)????????????18??,??????????,??????????????“???????????????”,?????,???“?????????????”??,?,????????????????

???“?????????????????????”????????,????????????,???,???50????????(??????????????????)????????,??????500?????,?????????1-3???????????,???0.3%-0.5%/???????????,????????????????????,????????,?,?????????????,??

???????????,“???”???????????????????????????????????????,???????????????????????????????,??,????????20?(???????)?????0.3%/?,20????????0.5%/?????????????????????????????????????????????????????????

????,??“?????”???20????????(???)?,???20???????,???????????????????,????????????????????????????????????(???) ?????????????:??????????????

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