精於

skillful in / proficient in / adept at

essence / extract / vitality / energy / semen / sperm / mythical goblin spirit / highly perfected / elite / the pick of sth / proficient (refined ability) / extremely (fine) / selected rice (archaic)

surname Yu / Taiwan pr. [Yu2]

(literary) Oh! / Ah!

(of time or place) in; at; on / (indicating any indirect relation) to; toward; vis-à-vis; with regard to; for / (indicating a source) from; out of / (used in comparison) than / (used in the passive voice) by

mastery of study lies in diligence (idiom). You can only master a subject by assiduous study. / Excellence in work is only possible with diligence. / Practice makes perfect.

to be proficient in the area of / skilled in this field