Which two statements about queuing mechanisms are true？ （）

A、FIFO queuing is only appropriate for slower serial interfaces

B、weighted fair queuing is the default queuing mechanism used for all but slower than E1 rate interfaces

C、only one queuing mechanism type can be applied to an interface

D、weighted fair queuing does not require the configuration of access lists to classify traffic  

E、flow-based weighted fair queuing provides for queues to be serviced in a round-robin fashion