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问题 单项选择题

化工设备选择和计算中，选择流体输送设备时首选的依据为______。

A．流量和扬程
B．流量、扬程和出口压力
C．被输送物料的性质
D．流体输送设备价格

答案

参考答案：C

改错题

You can speak to people on other side of the earth over the telephone with help of a satellite. They can help to take photos on the earth and produce maps. Some pictures taking by satellites show us the exact place where different metals can be found. They can also tell the differences between healthy plants or poor ones. This is a great help to the scientists work in forestry and in agriculture. Satellites benefit by out daily life. For example, satellites for broadcasting are used to sending radio and TV programmes from one part of the world to other. It is the satellites to make our world seem smaller.
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单项选择题

现行的《环境空气质量标准》(GB 3095—1996)中，二氧化氮的日平均浓度二级标准限值是( )。

A．0.04mg/m3(标态)

B．0.08mg/m3(标态)

C．0.10mg/m3(标态)

D．0.12mg/m3(标态)
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