关于子宫峡部哪项是错误的（）

A.峡部下端是组织学内口

B.峡部上端为解剖学内口

C.峡部下端是解剖学内口

D.子宫体和子宫颈之间是最狭窄部

E.子宫峡部于妊娠期晚期伸展为子宫下段

Networks can be interconnected by different devices. In the physical layer, networks can be connected by (11) 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 (12) ,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 (13) network layer, the router may be able to translate between the packer 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 (14) . As an example, gateways between Internet e-mail and X.400 e-mail must (15) the e-mail message and change various header fields.

14（）

A.syntax

B.semantics

C.language

D.format