甲乙两河,通过实测年径流资料的分析计算,得各自的年径流量均值、和均方差、如下:甲河:=100m/s,=42m/s;乙河:=1000m/s,=200m/s ,两河相比,可知
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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