Complex sentence: Showing early signs of musical talent, while still a schoolboy Massenet was admitted to France's principal music college, the Paris Conservatoire, where he studied under Ambroise Thomas, whom he greatly admired.
Split into simpler sentences: Showing early signs of musical talent, while still a schoolboy Massenet was admitted to France's principal music college, the Paris Conservatoire. There he studied under Ambroise Thomas, whom he greatly admired.