routing in circuit-switching networks has traditionally involved a static routing strategy with the use of（71）paths to respond to increased load . modern routing strategies provide more adaptive and flexible approaches . the routing function of a packet-switching network attempts to find the least-cost route through the network , with cost based on the number of （72）,expected delay , or other metrics in virtually all packet-switching networks , some sort f adaptive routing technique is used . adaptive routing algorithms typically rely on the（73）information about traffic conditions among nodes . in most cases , adaptive strategies depend n status information that is（74）at one place but used at another . there is a tradeoff here tween the quality of the information and the amount of（75）. the exchanged information itself a load on the constituent networks , causing a performance degradation.
(71)A.only
B.single
C.alternate
D.series
(72)A.hops
B.sites
C.members
D.points
(73)A.exchange
B.transportation
C.reception
D.transmissio
(74)A.rejected
B.collected
C.discarded
D.transmitted
(75)A.packets
B.information
C.data
D.overhead