12.对含有两个随机变量的同一批资料,既作直线回归分析,又作直线相关分析。令对相关系数检验的t值为tr,对回归系数检验的t值为tb,二者之间具有什么关系?()
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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