独立样本3×5列联表作χ2检验，其自由度是（）
A.6
B.8
C.10
D.12
E.15
参考答案：B
— Mike, what did our monitor say just now?
— Every boy and every girl as well as the teachers who _____ to visit the museum _____ asked to be at
the school gate before 6:30 in the morning. [ ]
A. is ; is
B. are; are
C. is; are
D. are; is
什么是机械噪声？
