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.

（69）处填（）。

A．syntax

B．semantics

C．language

D．format

公司新近任命原经营经理出任首席审计执行官。新任的审计执行官既不是国际注册内部审计师，也不是ⅡA的成员。内部审计活动的工作是严格按照审计执行官的要求开展的，而非ⅡA的标准。4名助理内部审计人员都是ⅡA的会员，但都不是国际注册内部审计师。依据ⅡA的道德规范，助理审计人员的最佳行动方案是：

A．鉴于他们都不是国际注册内部审计师，因此不需要遵守职业道德规范。
B．应遵守内部审计专业实务标准。
C．必须尊重组织的法律地位和道德目标，可忽视内部审计专业实务标准。
D．必须辞去他们的工作以避免不恰当的活动。