idea behind virtual circuits is to avoid having to choose a new （72） for every packet sent.
Instead, when a connection is established, a route from the （73） machine to the destination
machine is chosen as part of the connection setup and stored in tables inside the （74） . That
route is used for all traffic flowing over the connection, exactly the same way that the
telephone system works. When the connection is released, the virtual circuit is also
terminated. With connection-oriented service, each packet carries an （75） telling which
virtual circuit it belongs to.
（71）A. connectionless B. connection-oriented C. datagram D. telegram
（72）A. processor B. device C. route D. terminal
（73）A. source B. route C. destination D. host
（74）A. connections B. resources C. bridges D. routers
（75）A. address B. identifier C. interface D. element