He hit his head really hard in a car accident and died.
He had a serious head injury in an automobile accident and it was fatal.
ーHe hit his head really hard in a car accident and died.
「彼は交通事故で頭を強く打ち、亡くなった」
to hit one's head really hard で「頭を強く打つ」
car accident で「交通事故」
to die で「死ぬ」
ーHe had a serious head injury in an automobile accident and it was fatal.
「彼は交通事故で頭に大怪我を負い、亡くなった」
to have a serious head injury で「頭に大怪我を負う」
automobile accident で「交通事故」
fatal で「致命的な」
ご参考まで！
カナダ 
