以下有关栓剂说法错误的是（）

A.栓剂在常温下为固体

B.栓剂在人体内溶融于分泌液中逐渐释放药物

C.常用栓剂包括肛门栓、 * * 栓和 * * 栓

D.栓剂外观应完整光滑

E.栓剂只能起局部作用

Networks can be interconnected by different devices．In the physical layer，networks can be connected by (64) or Hubs, which just move the bits from one network to an identical net-work. One layer up we find bridgas and swiehes, which operate at data link layer. They can accept (65) , 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 (66) 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

(67) . As an example, gateways between Internet e-mail and X.400 e-mail must (68) the e-mail message and change various header fields.

64（）

A．reapers

B．relays

C．connects

D．modems