For something，we can understand when we are young but by the time we understand，we are no longer young.
有些事情，当我们年轻的时候无法懂得，当我们懂得的时候已不再年轻。
【相关单词短语讲解】
1. by the time到…的时候
(1) By the time I get home, Im too tired to do anything active.
我到家时累得无法动弹。
——《柯林斯高阶英汉双解学习词典》
(2) Her singing career was all washed up by the time she was 27.
她到27岁时歌唱生涯就告终了。
——《牛津高阶英汉双解词典》
【拓展：washed up】
（事业等）告吹的；完蛋：no longer successful and unlikely to succeed again in the future
Hes all washed up, but he still yells at everyone.
他彻底完蛋了，但仍旧对每个人大吼大叫。
——《柯林斯高阶英汉双解学习词典》
2. no longer不再
He could no longer hold back his tears.
他再也无法控制住眼泪。
——《牛津高阶英汉双解词典》
Many young people no longer feel they have a stake in society.
很多年轻人不再觉得他们与社会休戚相关。
——《牛津高阶英汉双解词典》
【拓展：have a stake in】
与…有利害关系
And the fact that they have a personal stake in the outcome makes them really pay attention.
因为与结果有个人利害关系，他们十分上心。
——四级真题- 12月 3卷 阅读A
【拓展：no longer与 no more 的区别】
no longer 和 not any longer 可以彼此互换，意思是“不再......”，no more 和 not any more 也可以彼此互换，意思也是“不再......”，但 no longer 偏重于指时间，no more 偏重于指程度。
1. 表示时间上不再延续，可以用 no longer，也可以用not...any longer，not...any more，例如：
He no longer lives here.
他不再住这儿。
= He doesn live here any longer.
= He doesn live here any more.
2. 表示程度，可用 no more、not ... any more 比如：
I am so tired that I can walk no more.
我太累了，一点也走不动了。
=I am so tired that I can walk any more.
3. 注意 no longer 的位置：只能放在谓语动词之前，如果有助动词的话，放在助动词之后实义动词之前。
I no long live with my parents.
我已不再和父母住在一起。
I will no longer live with my parents.
我将不会再和父母住在一起。
