Complex sentence: He practised with them for twelve years until 1940, when he became law clerk of the Legislative Assembly of Quebec, a position he held for four years before joining the law firm of Germain, Lapointe, Thibaudeau et Roberge.
Split into simpler sentences: He practised with them for twelve years until 1940, when he became law clerk of the Legislative Assembly of Quebec. He held that position for four years before joining the law firm of Germain, Lapointe, Thibaudeau et Roberge.