发愤忘食

wǒ céng jīng fā fèn wàng shí kè kǔ xué xí

我曾经发愤忘食，刻苦学习。

I was so immersed in my studies that I sometimes even forgot my meals.

yǒu de xué sheng yǒu shí hou shèn zhì fā fèn wàng shí

有的学生有时候甚至发愤忘食。

Some of the students were so immersed in their studies that they sometimes even forgot their meals.