食盐、食醋、纯碱等为家庭厨房中常用的物质．利用这些物质，你能完成的实验是（　　）

①检验自来水中是否含有氯离子  ②鉴别食盐和纯碱   ③鉴别烧碱和氢氧化钾

④除去热水瓶中的水垢          ⑤检验鸡蛋壳能否与酸反应．

A．③④⑤

B．②④⑤

C．②③④⑤

D．①③④⑤

(31) analysis emphasizes the drawing of pictorial system models to document and validate both existing and/or proposed systems. Ultimately, the system models become the (32) for designing and constructing an improved system. (33) is such a technique. The emphasis in this technique is process-centered. Systems analysts draw a series of process models called (34) . (35) is another such technique that integrates data and process concerns into constructs called objects.

A．Prototyping

B．Accelerated

C．Model-driven

D．Iterative