会议原本进展顺利，但突然停电打断了所有讨论。

The meeting was going well until a power outage ___supervened and interrupted all discussions.

就在我们准备出发时，一场暴雪突然降临，打乱了所有计划。

As we were ready to depart, a heavy snowstorm ___supervened, disrupting all our plans.