You’d better            English       .

A．practice speaking; as much as possible

B．practicing speaking; as often as possible

C．practice speaking; as good as possible

D．practice speak; as possible as you can

由两样本均数的差别推断两总体均数的差别，得到此差别具有统计意义的结论是指（）。

A．两样本均数差别有显著性

B．两总体均数差别有显著性

C．两样本均数和两总体均数的差别都有显著性

D．其中一个样本均数和它的总体均数差别有显著性

E．以上都不是