题目内容
实验组和对照组必须均衡,唯一不同的是
2021-10-11
A.观察指标
B.观察时间
C.实验因素
D.抽样误差
E.系统误差
试卷相关题目
SQL Error: select id,body,options from ***_enewstiku where sourceid='25429' and id < 2141974 and id<>'2141974' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='25429' and id > 2141974 and id<>'2141974' order by id asc limit 5