信用证有效地点为信用证指定的单据提交地点，即（）所在地。
A.议付行；
B.贴现行；
C.开证行；
D.以上都不对
参考答案：A, B, C
, I lost heart in English learning, but my teacher often said to me, "Keep on studying hard ,
and you'll succeed ." [ ]
A. At one time; in time
B. At one time; on time
C. At a time; in time
D. At a time; on time
有集中采暖的用户一般比无集中采暖的用户的用气量高一些，一般每年相差( )。
A．5%～10%
B．10%～20%
C．15%～25%
D．10%～15%
