题型:问答题 简答题 某省从3个水中氟含量不同的地区随机抽取10~12岁儿童,进行第一恒齿患龋率的调查,结果如下表:无效假设应为()A.B.μ1=μ2=μ3C.P1=P2=P3D.π1=π2=π3E.以上全不对 查看答案
题型:问答题 简答题 Not the way he did it but his words _____ criticized by people present. A.has B.had C.isD.were 查看答案