You never know what you can do till you try.事非经过不知难.

You never know what you can till you try.是驴子是马，拉出来遛遛。

You never know your luck.命运好坏不由己。

You roll my log and I'll roll yours.互相吹嘘.

You should, like a candle, burn yourself out to give light to others.要象蜡烛一样燃烧自己，照亮别人。

You'd better wise up.你最好放聪明点.

Young man may die but old men must die.年轻人可能会死，老年人难免不亡.

Youth is a blunder; manhood a struggle, old age a regret.青年冒失莽撞；成年发奋图强；老年遗憾懊丧.

Youth is life's seed-time.青年时代是人生的播种期.

Youth is the season of hope, enterprise, and energy, to a nation as well as an individual.青年时期对国家和个人都是希望、创业和精力充沛的时期.

Youth looks forward and age backward.青年人向前看，老年人向后看.

Zeal¹ without knowledge is a runaway² horse.缺乏知识之热诚犹如脱缰之马。

Zeal without knowledge is fire without light.有热情而无知识，犹如有火焰而无光芒.