常用来推断总体数量特征的统计量包括（）。
A.样本平均数
B.样本方差
C.样本标准差
D.样本比例
D.样本众数
参考答案：A, B, C, D
These are Christmas lights _________ our house.[ ]
A. off
B. at
C. on
I’d rather _________vegetables than __________ meat for lunch.
A．eat ; eating
B．eating ; eat
C．have ; eating
D．have ; have
