un.fail.ing Qn5feI7lIN adj (of a positive quality of someone's character) showing itself at all times 经久不衰的，不倦的，无穷无尽的，永恒的，忠贞不渝的 One of the good things about Amanda is that you can always rely on her unfailing enthusiasm. 阿曼达身上良好的品质之一是你可以永远相信她经久不衰的热心。