28. 關於付款條件〝Payment: by confirmed L/C 30 days after B/L date in favor of the seller, to be established prior to May 20, 2010, valid for negotiation within 20 days after the shipment date〞，下列敘述何者錯誤? (A)買方必須在5月20日之前開立保兌遠期信用狀 (B)裝運後20天內要去押匯 (C)付款條件為以賣方為受益人的信用狀 (D)付款期限為見票後30天