单选题 Hypothesis test can be divided into one-tailed test and two-tailed test. A onetailed hypothesis test may not have a:
A. "Iess than or equal to" alternative hypothesis.
B. "not equal to" alternative hypothesis.
C. "greater than" alternative hypothesis.

【正确答案】 B

【答案解析】[解析] 双边检验的原假设为“equal to”，备择假设为“not equal to”，拒绝域在两边。单边检验的备择假设可以是“less than”或“greater than”，也可以是“less than or equal to”或“great than or equal to”，因为在连续分布的情况下，落在具体某一个点的概率为0。