以下说法正确的有( )。

A．银货对付又称款券两讫、钱货两清

B．银货对付的主要目的是为了规避交收对手方交收违约带来的风险

C．银货对付的主要目的是为了简化操作手续

D．银货对付就是在交收过程中，当且仅当资金交付时给付证券，证券交付时给付资金

An internet is a combination of networks connected by (26) ．When a datagram goes from a source to a (27) ，it will probably pass many (28) until it reaches the router attached to the destination network．A router receives a (29) from a network and passes it to another network．A router is usually attached to several networks．When it receives a packet，to which network should it pass the packet The decision is based on optimization：Which of the available (30) is the optimum pathway

A．destination

B．resource

C．packet

D．source