CD-77型充电机可同时供两组充电,每组有两种充电电流即()mA。
A、100和200
B、200和300
C、100和300
D、300和400
参考答案:B
“无德无才是‘废品’,有德无才是‘半成品’,有才无德是‘危险品’,有德有才是‘精品’。”这一比喻表明[ ]
A、科学文化修养比思想道德修养更重要
B、思想道德修养比科学文化修养更重要
C、科学文化修养和思想道德修养是有机统一的
D、有德无才与有才无德都是部分意义上的人才
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