After the accident, it took him a week to regain consciousness.

regain 由前缀 re-（表示"重新"）和动词 gain（获得）组成，字面意思是"重新获得"。 consciousness 是名词，来自形容词 conscious（有意识的），指"意识状态"或"知觉"。 regain consciousness 意思是"恢复意识"，指从昏迷或无意识状态中苏醒过来。