《中国药典临床用药须知》规定必须做皮肤敏感试验的药品是（）

A.天花粉蛋白

B.链霉素注射剂

C.苯唑西林注射剂

D.注射用头孢菌素

E.细胞色素C注射剂

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.

（70）处填（）。

A．analyze

B．parse

C．delete

D．create