对制冷设备的材料质量进行检查,哪些要求是正确的是() A.氨制冷剂系统的管道、附件、

题型:多项选择题

问题:

对制冷设备的材料质量进行检查,哪些要求是正确的是()

A.氨制冷剂系统的管道、附件、阀门及填料和接触的零件,不得采用铜和铜合金材料,因为氨对铜和铜合金具有腐蚀作用

B.与制冷剂接触的密封垫片不得使用铝材,纯度较高的铝材也不可以

C.法兰、螺纹等处的密封材料,应选用耐油橡胶石棉板、聚四氟乙烯膜带、氯丁橡胶密封液等

D.氨制冷系统普遍采用无缝钢管,其内壁镀锌

E.氟利昂系统普遍使用纯铜管

考点:土木建筑工程建设工程安全生产技术建设工程安全生产技术题库
题型:多项选择题

按照亚洲的地理分区,日本和中国都属于                             [ ]

A.东南亚地区        

B.东亚地区      

C.中亚地区      

D.南亚地区

题型:多项选择题

强心苷增加心衰病人心排血量的作用是由于()

A.加强心肌收缩性

B.反射性地降低交感神经活性

C.反射性地增加迷走神经活性

D.降低外周血管阻力

E.反射性地兴奋交感神经

题型:多项选择题

原型生命周期对于某些特殊情况的应用可以采取灵活的做法,下述
Ⅰ.原型化必须从定义阶段开始 Ⅱ.可购买应用系统为初始原型
Ⅲ.对系统的子系统进行原型化 Ⅳ.仅对屏幕的原型化
哪个是对原型化不必要的约束

A.Ⅰ

B.Ⅱ

C.Ⅲ

D.Ⅳ

题型:多项选择题

阳极旋转速度的公式是n=(120f/P·(1-s),式中P的取值是

A.1
B.2
C.3
D.4
E.5

题型:多项选择题

One day a businessman was going to another town to sell his goods (货物). He decided to take ten servants(仆人) with him. They would carry his goods and also some food to eat on the way. He said to one of the servants, "You are the smallest and the shortest one. You may carry the lightest load (担子). "The servant thanked him but took the biggest load. This was the bread to eat on the way.
The man said, "You’re foolish. That is the heaviest load." But the servant took up the load happily, and so they set off. After four hours they stopped for a rest. They all ate some of the bread. Then there was less bread for the servant to carry. Every time they ate some bread, the load became smaller and lighter. At the end of the trip, the servant had nothing to carry, and all the other servants still had a lot of things to carry.

The servant who carried food was a ______ man.

A. kind


B. foolish


C. clever

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