不可撤销信用证bù kě chè xiāo xìn yòng zhèngbukechexiaoxinyongzhengirrevocable letter of creditCharacters in this word不no, not, un-信to trust, to believe可may, can, -able撤to omit用to use, to employ, to apply证to prove, to verify销to fuse, to meltStudy it in Yanamino