The early ambitions of youthful enthusiasm soon become tempered with realism.之前年少时对理想抱负怀有的一腔热情很快便被现实浇灭。At the time I admired his youthful enthusiasm.当时我很羡慕他那年轻人特有的热情。She still manages to bring a youthful enthusiasm and energy to her work.她对工作仍有青年人的热忱和活力。