多重比较如果用f检验的方法进行推断，则会使（）
A.α↑
B.β↑
C.α，β均增大
D.α，β均减小
E.以上均不正确
参考答案：A
微氧环境CO2含量应为
A．3％～5％
B．5％～10％
C．15％
D．20％
E．15％～20％
Little ____ about his own safety, though he was in great danger himself. [ ]
A. does he care
B. did he care
C. he cares
D. he cared
