统计发挥认识社会作用的一个重要手段是（）
A.统计分析
B.统计指标
C.统计质标
D.统计描述
参考答案：B
由4个单元组成串联系统，若每个单元工作1000小时的可靠度为0.9，则系统工作1000小时的可靠度为（）。
A．0.5561
B．0.6561
C．0.7561
D．0.9000
根据答语写出特殊疑问句。
1. —_____ is your English teacher?
—Miss Gao Xing is.
2. —_____ do you often go to bed?
—At 9: 30.
3. —_____ do you have a sports meeting every year?
—It's on September 29th.
4. —_____ does your father work?
—He works in a hospital.
5. —_____ is your favourite food?
—Sandwiches.
