Complex sentence: Students are allowed to take general elective courses (e.g. art, music, business, et cetera) all four years at GHS, but are only allowed to take certain subject electives (e.g. English) in Junior and Senior years.
Split into simpler sentences: Students are allowed to take general elective courses (e.g. art, music, business, et cetera) all four years at GHS. Students, however, are only allowed to take certain subject electives (e.g. English) in Junior and Senior years.