甲乙两流域除河网密度甲大于乙的外,其它流域下垫面因素和气象因素均相同,对相同降雨所形成的流量过程,甲流域的洪峰流量比乙流域的
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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