单项选择题 A researcher wants to conduct a before/after study on 11 subjects to determine if a treatment results in any difference in scores. The null hypothesis is that the average difference is zero while the alternative hypothesis is that the average difference is not zero. Scores are obtained on the subjects both before and after the treatment. After subtracting the after scores from the before scores, the average difference is calculated to be –2.40 with a sample standard deviation of 1.21. Assume that the differences are normally distributed in the population. The degrees of freedom for this test are _______.

多项选择题 下面属于施工验收文件的是（） A、检验批质量验收记录  B、单位（子单位）工程质量竣工验收记录 C、单位（子单位）工程观感质量检查记录 D、单位（子单位）工程质量控制资料核查记录

多项选择题 动态控制包含哪些内容？ A、投资目标值与实际值的比较 B、各类投资控制报告和报表的制定 C、投资偏差的分析 D、投资偏差纠正措施的采取