【题目】 to smart phones just before bed, as a research says recently, can lead to poor night's sleep.
A.Being exposed
B.Exposed
C.Having exposed
D.To expose

【答案】A
【解析】句意：据最近的一次调查报道，睡前接触智能手机会导致晚上睡不好。人是被暴露在手机辐射下的，应用被动语态。Being exposed to…在句中作主语，应用动名词。故选A项。