下列关于我国在新时期大力发展旅游业的政策导向表述有误的是( )。

A．全面发展国内旅游，继续推进红色旅游

B．合理开发和保护旅游资源，改善基础设施

C．推进重点旅游区，旅游线路建设

D．继续发展观光旅游、专题旅游，鼓励开发出境旅游

Networks can be interconnected by different devices. In the physical layer, networks can be connected by (66) or Hubs, which just move the bits from one network to an identical network. One layer up we find bridges and swiches, which operate at data link layer. They can accept (67) ,examine the MAC address, and forward the frames to a different network while doing minor protocol translation in the process. In the network layer, we have routers that can connect two netwoks. If two networks have (68) network layer, the router may be able to translate between the packet formats. In the transport layer we find transport gateway, which can interface between the two transport connections. Finally, in the application layer, application gateways translate message (69) . As an example, gateways between Internet e-mail and X. 400 e-mail must (70) the e-mail message and change various header fields.

（68）是（）

A.special

B.dependent

C.similar

D.dissimilar