烧伤合并应激性溃疡出血时，应避用以下药物（）

A.H2受体阻滞剂

B.大量维生素A

C.肾上腺皮质激素

D.凝血酶

E.奥美拉唑（洛赛克）

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.

（69）是（）

A.syntax

B.semantics

C.languages

D.format