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问题 选择题

把稀硫酸倒在亚硫酸钠粉末上，能使反应的最初速率加快的是

A．增大亚硫酸钠粉末的量。

B．硫酸浓度增大一倍，用量减少到原来的1/2。

C．硫酸浓度不变，用量增大一倍。

D．使反应在较低温度下进行。

答案

答案：B

考查反应速率的影响条件

A：固体的量不能影响反应速率

B：增大反应物的浓度可加快反应速率，正确

C：浓度不变，反应速率不变

D：降温时，反应速率降低

答案为B

单项选择题

It should go without saying that the focus of UML is modeling. However, what that means, exactly, can be an open-ended question. (71) is a means to capture ideas, relationships, decisions, and requirements in a well-defined notation that can be applied to many different domains. Modeling not only means different things to different people, but also it can use different pieces of UML depending on what you are trying to convey. In general, a UML model is made up of one or more (72) . A. diagram graphically represents things, and the relationships between these things. These (73) can be representations of real-world objects, pure software constructs, or a description of the behavior of some other objects. It is common for an individual thing to show up on multiple diagrams; each diagram represents a particular interest, or view, of the thing being modeleD. UML 2.0 divides diagrams into two categories: structural diagrams and behavioral diagrams. (74) are used to capture the physical organization of the things in your system, i.e., how one object relates to another. (75) focus on the behavior of elements in a system. For example, you can use behavioral diagrams to capture requirements, operations, and internal state changes for elements.

（73）处填（）。

A．things

B．pictures

C．languages

D．diagrams
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单项选择题

安装在驾驶室、海图室及其他噪声敏感区内的航行设备及其部件所产生的噪声级应不超过（）dB。

A、80

B、75

C、70

D、65
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