单项选择题
A.跟单信用证;清洁检验报告 B.跟单汇票;清洁提单 C.跟单信用证;清洁提单 D.跟单汇票:清洁检验报告
A.until B.since C.just D.but
A.isn't it B.is it C.it isn't D.it is