Complex sentence: Only a few of Riverdale High's staff appear regularly in the comics, others have appeared for short periods or sporadically over the years, particularly in the 1970s, and late 1980s through early 1990s.
Split into simpler sentences: Only a few of Riverdale High's staff appear regularly in the comics. Others have appeared for short periods or sporadically over the years, particularly in the 1970s, and late 1980s through early 1990s.