题目内容

In a domestic fresh water system, the pump starters are controlled by () switches which operate when the pressure in the tank varies within predetermined limits as water is drawn off.

A. water level
B. water flow
C. temperature
D. pressure

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哪些动物可以感染高致病性禽流感?

抽油机每个地脚螺栓旁对应放置()垫铁。

A. 一组
B. 两组
C. 三组
D. 四组

确定组数多少和组距大小的原则是?

总体有n个秩次1,2……n。若n个秩中有相同秩(如1,2,4,4,4,6,7……n),其均数和方差是否会改变?

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