译文及注释：
译文：
古人学习知识不遗余力，年轻时下功夫，到老年才有所成就。
The ancients spared no effort in learning knowledge. They worked hard when they were young and only achieved something in their old age.
从书本上得来的知识毕竟不够完善，要透彻地认识学习知识这件事还必须亲自实践。
The knowledge gained from books is ultimately not sufficient. To truly understand the process of learning knowledge one must personally practice it.
注释：
示：训示、指示。
示: to instruct to guide.
子聿(yù)：陆游的小儿子。
Ziyu (yù): Lu You's youngest son.
学问：指读书学习，就是学习的意思。
Xuewen: refers to studying and learning.
遗：保留，存留。
Yi: to retain to preserve.
无遗力：用出全部力量，没有一点保留，不遗余力、竭尽全力。
Wuyi li: to use all one's strength without any reservation to spare no effort.
少壮：青少年时代。
Shaozhuang: youth adolescence.
工夫：做事所耗费的时间。
Gongfu: the time and effort spent on doing something.
始：才。
Shi: only just.
纸：书本。终：到底，毕竟。
Zhi: books. Zhong: after all ultimately.
觉：觉得。
Jue: to feel to think.
浅：肤浅，浅薄，有限的。
Qian: shallow superficial limited.
绝知：深入、透彻的理解。
Jue zhi: deep thorough understanding.
行：实践。
Xing: to practice.
躬行：亲身实践。
Gongxing: to personally practice.