a difficult (to solve) case

largely; mostly

a lot / a majority

excellent, outstanding, superior

be good at (a thing); be superior to (a person)

(law enforcement) a detective / (usually attributive) criminal matters

solution, settlement / (music) Progression from dissonance to consonance; a chord to which such progression is made; resolution

(transitive) solve, resolve, settle (a problem, a trouble, a criminal case) / (intransitive) be solved, be settled / (intransitive) can be solved; be soluble

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