懸樑刺股

jyun4 loeng4 ci3 gu2

to study assiduously and tirelessly (idiom) · see also 頭懸梁，錐刺股|头悬梁，锥刺股[tou2 xuan2 liang2 , zhui1 ci4 gu3]{tau4 jyun4 loeng4 ，zeoi1 ci3 gu2}