句子使用了 'If... will...' 的条件时态结构，'in vain' 这一短语增强了情感色彩，表达悔恨之情。
Time is like water in a sponge; if you are willing to squeeze, there is always some. — Lu Xun
We only live once in this world, so we should cherish our time. We must live a genuine life, a life of value. — Pavlov
Do not idle away your youth, only to regret it in vain when your hair turns white. — Yue Fei
Between today and tomorrow, there is a long stretch of time; while you still have the energy, learn to handle matters swiftly. — Goethe
If you do not strive when you are young, you will only grieve in vain when you are old.
Time is gold, but gold cannot buy time.
If you do not rise early, you ruin your day; if you do not study in youth, you ruin your life.
Flowing water never returns, and time never comes back.
Time is a silent file.
Ordinary people waste their minds killing time, while capable people use their wits to make use of time.
Do not waste time; do something useful every moment, and abandon all unnecessary behaviors.
Time is life; needlessly wasting others' time is no different from robbery and murder.
Fragmented time can indeed achieve great things.
Time flies swiftly; how can I afford to wait?
Time is a loan that even the most creditworthy borrower cannot repay.
The more one knows the value of time, the more acute the pain of lost time becomes.
Those who are good at using time always find plenty of it.
Cherishing time can make life more valuable.
Seizing today is better than two tomorrows.
Today is the most precious, yet also the easiest to lose.
时间就像海绵里的水，只要愿挤，总还是有的。——鲁迅
在世界上我们只活一次，所以应该爱惜光阴。必须过真实的生活，过有价值的生活。——巴甫洛夫
莫等闲，白了少年头，空悲切！——岳飞
在今天和明天之间，有一段很长的时间；趁你还有精神的时候，学习迅速办事。——歌德
少壮不努力，老大徒伤悲。
一寸光阴一寸金，寸金难买寸光阴。
早晨不起误一天的事，幼时不学误一生的事。
逝水不会有重归，时间不会有重返。
时间是没有声音的锉刀。
庸人费心将是消磨时光，能人费尽心计利用时间。
不浪费时间，每时每刻都做些有用的事，戒掉一切不必要的行为。
时间就是性命，无端的空耗别人的时间，其实无异于谋财害命。
零碎的时间实在可以成就大事业。
光阴易逝，岂容我待。
时间是一笔贷款，即使再守信用的借贷者也还不起。
一个人越知道时间的价值，越倍觉失时的痛苦。
善于利用时间的人，永远找得到充裕的时间。
珍惜时间可以使生命变得更有价值。
抓住今天，胜似两个明天。
最珍贵的是今天，最容易失掉的也是今天。