Alternative spelling of 日日: day by day

every day, daily

hard (academic) study

to study hard

mathematics (field of study)

he / distal demonstrative, something far off removed from both speaker and listener: that / boyfriend

distal demonstrative, something far off removed from both speaker and listener: that, yon / particularly, male personal third person pronoun: he / by extension from he: boyfriend

he; boyfriend

self-improvement, improving one's own skills and abilities

(mathematics) pure mathematics