the crux of the matter isa discourse marker meaning 'the central or most important point of the issue'The crux of the matter is whether renewable energy can scale fast enough to meet global demand.NoteThe crux of the matter is whether renewable energy can scale fast enough to meet global demand.Elon.io is an online learning platformWe have an entire course teaching TOEFL Academic Vocabulary grammar and vocabulary.Start learning TOEFL Academic Vocabulary now