甲乙两国边界附近爆发部落武装冲突,致两国界标被毁,甲国一些边民趁乱偷渡至乙国境内。依相关国际法规则,下列哪一选项是正确的?
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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