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

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

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

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