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问题 选择题

下列说法不正确的是

A．常温下，氧气与所有金属都能反应

B．棉花属于天然有机高分子材料

C．结晶水合物属于纯净物

D．中和反应一定有盐和水生成　　

答案

答案：A

A、常温下，氧气不与金等反应，故A说法不正确；

B、棉花属于天然有机高分子材料，故B说法正确；

C、结晶水合物属于纯净物，故C说法正确；

D、中和反应是指酸和碱反应生成盐和水的反应，故D说法正确。

单项选择题

Ravi, like many project (1) , had studied the waterfall model of software development as the primary software life-cycle (2) . He was all set to use it for an upcoming project, his first assignment. However, Ravi found that the waterfall model could not be used because the customer wanted the software delivered in stages, something that implied that the system had to be delivered and built in (3) and not as (4) .

The situation in many other projects is not very different. The real world rarely presents a problem in which a standard process, or the process used in a previous project, is the best choice. To be the most suitable, an existing process must be (5) to the new problem.

A development process, even after tailoring, generally cannot handle change requests. To accommodate change requests without losing control of the project, you must supplement the development process with a requirement change management process.

（3）处填（）。

A．parts

B．modules

C．software

D．a whole
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单项选择题

高频振荡通气的频率设置一般为（）

A.200～400次／分

B.400～600次／分

C.600～900次／分

D.100～200次／分

E.80～100次／分
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