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问题 单项选择题

一根轻质弹簧竖直悬挂一小球，小球和弹簧的受力如图所示，下列说法正确的是（）

A.F1的施力者是弹簧

B.F2的反作用力是F3

C.F3的施力者是地球

D.F4的反作用力是F1

答案

参考答案：B

解析：

据题意，F1的施力者是地球，选项A错误；F2的反作用力是F3故选项B正确；F3的施力者是小球，故选项C错误；弹簧对天花板的拉力，故选项D错误。

多项选择题

编制投标文件的准备工作包括( )。

A．投标单位概况

B．认真研究招标文件

C．充分了解工程项目的有关信息

D．对本项目的理解

E．合理选配执行任务的咨询专家
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单项选择题

The purpose of the requirements definition phase is to produce a clear, complete, consistent, and testable (46) of the technical requirements for the software product.
During the requirements definition phase, the requirements definition team uses an iterative process to expand a broad statement of the system requirements into a complete and detailed specification of each function that the software must perform and each (47) that it must meet. The starting point is usually a set of high-level requirements from the (48) that describe the project or problem.
In either case, the requirements definition team formulates an overall concept for the system and then defines (49) showing how the system will be operated, publishes the system and operations concept document, and conducts a system concept review (SCR).
Following the SCR, the team derives (50) requirements for the system from the high-level requirements and the system and operations concept. Using structured or object-oriented analysis the team specifies the software functions and algorithms needed to satisfy each detailed requirement.

A．function

B．definition

C．model

D．statement
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