如图所示，位置固定的轻绳拉住轻杆的右端B点，轻绳与竖直墙壁间的夹角是53°。轻杆左端固定在铰链上，可以绕铰链转动。而铰链在墙壁上的安装位置可以任意选定，同时可以根据需要选用合适长度的轻杆，以使轻杆受到的压力最小。现将一个质量是100kg的重物挂在B点。g取10 m/s²，则轻杆承受的最小压力是：

A．

B．

C． 800N

D． 600N

The purpose of the requirements definition phase is to produce a clear, complete, consistent, and testable （） 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 （） that it must meet. The starting point is usually a set of high-level requirements from the （） that describe the project or problem. In either case, the requirements definition team formulates an overall concept for the system and then defines （） 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 （） 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.

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 （） that it must meet.

A．criterion

B．standard

C．model

D．system