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问题 选择题

设NA代表阿伏加德罗常数，下列说法正确的是[ ]

A．12g C60中含有60NA个电子

B．1mol HNO3见光分解，转移电子数为4NA

C．48g O2和48g O3含有的原子数分别为2NA和3NA

D．60g SiO2高温下与足量纯碱反应最多可释放出的气体分子数为NA

答案

答案：D

单项选择题

跳闸的原因（）。

A.电机超负荷

B.冷却水不足或中断

C.抽空

D.叶轮入口或泵的入口有异物堵塞
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单项选择题

The software architecture of a program or computing system is the structure or structures of the system, which comprise software （1）, the externally （2）properties of those components, and the relationships between them. The architecture is not the operational software. Rather, it is a （3） that enables a software engineer to: analyze the （4）of the design in meeting its stated requirements, consider architectural alternatives at a stage when making design changes is still relatively easy, and reduce the（5） associated with the construction of the software.

（4）是（）

A.changeability

B.effectiveness

C.testability

D.functionality
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