Complex sentence: Various proscriptive authorities, such as style guides and teachers, make pronouncements on the correctness of many constructions; disputes arise when these authorities disagree with each other, or with actual usage by a population of speakers.
Split into simpler sentences: Various proscriptive authorities such as style guides and teachers make pronouncements on the correctness of many constructions. Disputes arise when these authorities disagree with each other or with actual usage by a population of speakers.