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问题 单项选择题

磷酸可待因与浓硫酸及三氯化铁试液共热，显蓝色，是因为（）

A.酚羟基与三氯化铁生成配合物

B.酚羟基被三氯化铁氧化

C.菲环脱水产物被三氯化铁氧化

D.醚键断裂生成酚羟基与三氯化铁生成配合物

E.醚键断裂生成羟基

答案

参考答案：D

单项选择题 共用题干题

The traditional model for systems development was that an IT department used (1) which is a process-centered technique, and consulted users only when their input or approval was needed. Compared with traditional methods, many companies find that JAD allows key users to participate effectively in the (2). When properly used, JAD can result in a more accurate statement of system requirements, a better understanding of common goals, and a per commitment to the success of the new system. RAD is a team-based techruque that speeds up information systems development and produces a functioning information system. While the end product of JAD is a(an) (3), the end product of RAD is the (4). The RAD model consists of four phases. During the (5), users interact with systems analysts and develop models and prototypes that represent all system processes, outputs, and inputs.

空白（2）处应选择（）

A.initial scope definition

B.requirements modeling process

C.object modeling process

D.architecture design process
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单项选择题

发生多普勒效应必须具备的基本条件（）

A.有声源

B.有接收体

C.声源与接收体产生相对运动

D.有强的反射源与散射源

E.以上均是
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