【经】 对开信用证书, 转开信用证书

back-to-back back to back back come back to earth trace back to back to square one back against (on to) back-to-nature go back to come back to life date back to bring back to health back-to back credit back-to-back credit back to back credit of credit back to back credit export first back-to-back letter of credit back to back credit import first back-to-back testing back-to-back circuit back to back diodes back-to-back test back-to-back starting