Complex sentence: It is the largest and the most cosmopolitan city in the South Pacific and has become an important regional centre; students from the Pacific region and a growing expatriate community make up a significant portion of the city's population.
Split into simpler sentences: It is the largest and most cosmopolitan city in the South Pacific and has become an important regional centre. Students from the Pacific region and a growing expatriate community make up a significant portion of the city's population.