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问题 问答题 简答题

简述室内消火栓给水系统一般由哪几个部分组成。

答案

参考答案：室内消火栓给水系统一般由水枪、水带、消火栓、消防水喉、消防管道、消防水池、水箱、增压设备和水源等组成。

填空题
已知随机变量ξ～B(2，
1
3
)，η=3ξ-1．则Eη的值为______．
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单项选择题

In order to increase revenues, a cell-phone company has decided to change its fee structure. Instead of charging a flat rate of $20 per month and $0.05 for every minute over 200 minutes, the company will now charge $50 per month for unlimited usage. Which of the following is a consideration that, if true, suggests that the new plan will not actually increase the company’s revenues ？（）

A. A rival company, which charges no start-up fee, offers an unlimited calling plan for $40 per month.

B. Two-thirds of the company’s customers use less than 500 minutes per month.

C. Studies have shown that customers using unlimited calling plans will increase their monthly usage of minutes by over 50 percent.

D. One-fifth of the company’s customers use in excess of 1,000 minutes per month.

E. In recent months the company has received several complaints of insufficient signal strength and poor customer service.
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