若ac2>bc2,则a( )b。
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____ their service, the workers of the hotel are active in learning English. [ ]
A. Improving
B. To improve
C. Improve
D. Having improved
两样本均数比较的t检验,t<t0.05/2,v,则正确结论是()。
A.两样本均数不相等
B.两总体均数不相等
C.两样本均数相等
D.两总体均数相等
E.两总体均数差别很小