安装空调设备的机房可以堆放杂物，但环境应整洁，设备周围应留有足够的维护空间。（）
参考答案：错
-I'll be away on a business trip. Would you mind looking after my pet dog?
-_____[ ]
A. OK,I'd be glad to
B. OK.I've no time
C. No,I won't do that
D. Yes,I'd like to
同一总体的两个样本中，以下哪种指标值小的其样本均数估计总体均数更可靠？（）
A.Sx
B.S
C.x
D.CV
E.S2
