For（1） service, we need a virtual-circuit subnet. Let us see how that works. The idea behind virtual circuits is to avoid having to choose a new （2） for every packet sent. Instead,when a connection is established, a route from the （3）machine to the destination machine ischosen as part of the connection setup and stored in tables inside the（4）That route is used forall 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-orientedservice, each packet carries an （5）telling which virtual circuit it belongs to.

（5）是（）

A.address

B.identifier

C.interface

D.element

下列哪个账户肯定不可以跨网点取款（）。

A.凭密支取的活期存折

B.凭密凭证支取的定活两便存单

C.凭密支取的定活两便存单

D.凭密凭印支取的定活两便存单