痤疮的好发部位为()
A.面部
B.颈部
C.胸部
D.背部
E.肩部
参考答案:A
标准误表示( )
A.集中趋势指标B.离散趋势指标C.抽样误差指标D.假设检验指标E.样本计量指标
It is required that no smoking ______ in the school.
A.was allowed
B.be allowed
C.would be allowed
D.had been allowed