Definition: If something dangerous or unpleasant breaks out, it suddenly starts. Level: B2
战争于1914年爆发。
War ___broke ___out in 1914.
昨晚工厂发生了一场火灾。
A fire ___broke ___out in the factory last night.
抗议期间爆发了暴力事件。
Violence ___broke ___out during the protest.
