甲是国内运输企业,乙是国外运输企业,丙委托甲和乙运输,甲是起运方,乙负责国外运输,甲乙丙都签了全程运输单,以下说法正确的有(
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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