Hai cercato la traduzione di 彼らの大部分は戻る da Giapponese a Inglese

most of them return 彼らの大部分は戻る although it's unlikely それ ありそうもないが you will ever fully recall the events あなた 出来事を完全に思い出すだろう around your accident あなたの 事故の周りで
most of them return, although it's unlikely you will ever fully recall the events around your accident.

表面上、本書の大部分は一連の事例の変遷を記録したものである。
on the surface the book consists mostly of a series of case histories.