题干

—_____ do you go online, Mary?

— Twice a week.

A:How long

B:How often

C:How many

D:How much

上一题 下一题 0.0难度 选择题 更新时间:2017-06-01 04:41:30

答案(点此获取答案解析)

B

同类题1

若随机变量x的分布列如下表所示,设h = 2x + 3,则h的期望值为
x
-1
0
1
P


a