有限的器官供体与大量需要移植器官的患者之间存在供不应求的矛盾。因此，对有限器官供体的分配存在着尖锐的伦理问题尽管争论激烈，但在下列争论的问题中有一点是绝大多数国家明确反对的

A．有限的器官供体应根据什么原则进行分配

B．谁应优先得到器官

C．由谁做出裁决

D．根据什么原则裁决

E．使器官供体商品化，以扩大移植器官的来源

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