3个样本频率比较,,可以认为()。
A.各总体频率不全相等
B.各总体频率均相等
C.各样本频率不全相等
D.各样本频率均不相等
E.各总体频率全不相等
参考答案:A
腐烂的水果散发出酒味,主要是由什么菌引起的? [ ]
A.乳酸菌
B.单细胞酵母菌
C.醋酸菌
D.青霉菌
Our classroom _____ every day, so it's very clean. [ ]
A. cleans
B. is cleaning
C. is cleaned
D. cleaned