OSI参考模型共分为７层，其中最低层是物理层，最高层是

A．传输层

B．会话层

C．网络层

D．应用层

The software architecture of a program or computing system is the structure or structures of the system, which comprise software （11）, the externally （12） properties of those components, and the relationships between them. The architecture is not the operational software. Rather, it is a （13） that enables a software engineer to: analyze the （14） of the design in meeting its stated requirements, consider architectural alternatives at a stage when making design changes is still relatively easy, and reduce the （15） associated with the construction of the software.

（13）处填（）。

A. framework

B. deliverables

C. representation

D. semantic models