When he was young， he used to hard at his lessons.
A. devote to working
B. devote himself to work
C. be devoted to work
D. be devoted to working
网友回答
A. devote to working
B. devote himself to work
C. be devoted to work
(答案→)D. be devoted to working
解析：当他年轻的时候，他常常刻苦的学习功课。Used to do“过去常常”，devote oneself to doing或be devoted to doing致力于做…，所以选D。