Select the statements that correctly express the meaning of the UCP。（）

A.An L/C is independent of relative contract even if it is expressly referred to by the L/C
B.If the L/C opening application bears any ambiguity in its instruction, the issuing bank should bear the risk to issue or amend the L/C
C.If the applicant has accepted the discrepancies, the issuing bank can still refuse the documents
D.Once a beneficiary accepts an L/C he must execute it