基本解释[經濟學]光單信用証英汉例句雙語例句Clean letters of credit are mainly used in non-trade settlement, while documentary credits are generally used in commodity trade.光票信用証主要用於非貿易結算，而在商品貿易中一般使用跟單信用証付款。documentary clean credit更多例句专业释义經濟學光單信用証