when while as then

来源：百度知道编辑：UC知道时间：2024/05/25 13:00:40

i was about to go back to sleep ________suddenly my bedroom became as bright as day.
A. when B. while C. then D.as
答案应选什么，为什么？？？
望详细解释啊

i was about to go back to sleep ( C then )suddenly my bedroom became as bright as day.
A. when B. while C. then D.as
我差不多快要去睡觉的时候,然后突然我的卧室变得像白天一样亮