下列语句中不正确的是（　　）

A．线段AB与线段BA表示相同的线段

B．∠AOB与∠BOA表示相同的角

C．一个锐角与一个钝角的和是一个平角

D．延长线段AB到C，使得BC=2AB

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．

A．semantic models
B．weak entities
C．data schemas
D．business models