[经] clean bill of draft, clean bill of exchange

bù fù tí dān de huì piào ㄅㄨˋ ㄈㄨˋ ㄊㄧˊ ㄉㄢ ㄉㄜ˙ ㄏㄨㄟˋ ㄆㄧㄠˋ