Years bring wisdom.
年长智也增。

Yesterday is dead, forget it; tomorrow does not exist, don't worry; today is here, use it.
昨天已经消逝，把它忘掉；明天还未来到，不必烦恼；今天就在眼前，把它用好。

Yesterday will not be called again.
光阴一去不复返。

You are the greatest enemy if you are a coward, but if you are brave, you are your greatest friend.
如果你是胆小鬼，你就是自己最大的敌人；如果你是勇敢者，你就是自己最好的朋友。

You can do more than strike while the iron is hot; you can make the iron hot by striking.
铁热时，你能做的不止是锤打，而锤打可使铁热。

You can fool some of the people all the time, and all of the people some of the time; but you can't fool all of the people all the time.
你可以一直愚弄一些人，甚至可以在某个时期愚弄所有的人；但不能一直愚弄所有的人。

You cannot clap with one hand.
孤掌难鸣。

You cannot flay the same ox twice.
一头牛不能剥两次皮。

You cannot have two forenoons in the same day.
一日之中不可能有两个上午。

You cannot judge a tree by its bark.
人不可貌相。

You cannot make a crab walk straight.
江山易改，本性难移。

You cannot sell the cow and sup the milk.
你不可能出售乳牛，同时又要喝牛奶。

You can take a horse to the water but you cannot make him drink.
马到河边不喝水，逼马低头亦枉然。

(不要逼人做他不愿做的事) You can't eat your cake and have it.
不能既要吃饼，又要把饼保存。

You can't make bricks without straw.
没有稻草，制砖难搞。

You can't make omelets (or omeletts) without breaking eggs.
有失才有得。

You have no goats, and yet you sell kids.
你虽无老山羊，却出卖小山羊。

You make the failure complete when you stop strying.
不再努力之时，就是完全失败之日。

You may force a man to shut his eyes, but you cannot make him sleep.
你可以迫人闭眼，但不能使他睡觉。

You may go farther and fare worse.
一动不如一静。

You may know the horse by his harness.
欲知马如何，可看套马索。

You must not pledge your own health.
切不可把健康作孤注一掷。

You must reap what you have sown.
种瓜得瓜，种豆得豆。

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

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

You (or One) cannot make a silk purse out of a sow's ear.
粗瓷碗雕不出细花来。

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

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。

Youth means limitless possibilities.
年轻意味着无限希望。

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

Zeal without knowledge is fire without light.