A.delay sensitive packets are given preferential treatment
B.the default policy identifies a delay sensitive class and default class
C.the default policy identifies a delay sensitive class， best effort class， and default class
D.the model is highly scalable
E.the model is still predominant on the internet F the model provides guaranteed service

A.CAC is implemented in the call setup phase to allocate bandwidth resources
B.CAC is implemented in the call maintenance phase to allocate bandwidth resources
C.CAC is utilized during the call teardown phase to ensure that all resources have been released
D.CAC uses the Cisco RSVP （Resource Reservation Protocol） Agent to integrate call-processing capabilities with the underlying network infrastructure
E.CAC is implemented in the call setup phase to determine the destination of the call