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 switches, 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 networks. 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 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.

（74）处填（）。

A．rules

B．principles

C．scenarios

D．scenes

如图，赵某，43岁，咽痛伴发热、头痛2天就诊，T38．3℃，检查见口咽粘膜急性充血腭弓、腭垂水肿、咽后壁淋巴滤泡红肿，颌下淋巴结肿大、轻压痛，根据其临床表现初步考虑为（）

A.急性扁桃体炎

B.急性咽炎

C.急性-喉炎

D.急性会厌炎

E.樊尚咽峡炎