[单项选择题] It is impossible for us to extend this Letter of Credit, which expires ______ December 30.
A.on
B.in
C.at
D.for
正确答案:A

[单项选择题] It is impossible for us to extend this Letter of Credit, which expires ______ December 30.
A.on
B.in
C.at
D.for
正确答案:A