An architectural style defines as a family of such systems in terms of a（71）of structural organization．More specifically，an architectural style defines a vocabulary of（72）and connector types，and a set of（73）on how they can be combined.For many styles there may also exist one or more（74）that specify how to determine a system’s overall properties from the properties of its parts．Many of architectural styles have been developed over the years.

       The best-known examples of（75）architectures are programs written in the Unix shell.

       （71）A．pattern

       B．data flow

       C．business process

       D．position level

       （72）A．metadata

       B．components

       C．models

       D．entities

       （73）A．functions

       B．code segments

       C．interfaces

       D．constraints

       （74）A．semantic models

       B．weak entities

       C．data schemas

       D．business models

       （75）A．event-based

       B．object-oriented

       C．pipe-and-filter

       D．layered